The most common and most likely answer to this crossword clue is the 5 letter word NINJA
N
I
N
J
A
More clues leading to the result NINJA
- Girl trapping judge’s assassin
- Covert mercenary in position in Jamaica
- Assassin hiding in town in Japan
- Eastern assassin in prison in Japan
- Killer policeman in Jamaica is hiding
- Assassin popular in New Jersey area
- Assassin arrested by Lenin jailed
- Assassin infiltrating town in Japan
- One involved in assassination in Japan?
- Martial art expert in town in Japan
Buddy explains!

The straight part
We know that "Covert mercenary" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case covert mercenary = ninja.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does NINJA mean?
NINJA noun- An adult male human.
- (collective) All human males collectively: mankind.
- A human, a person of either gender, usually an adult. (See usage notes.)
- (collective) All humans collectively: mankind, humankind, humanity. (Sometimes capitalized as Man.)
- A member of the genus Homo, especially of the species Homo sapiens.
- An male person, usually an adult; a (generally adult male) sentient being, whether human, supernatural, elf, alien, etc.
- An adult male who has, to an eminent degree, qualities considered masculine, such as strength, integrity, and devotion to family; a mensch.
- Manliness; the quality or state of being manly.
- A husband.
- A lover; a boyfriend.
- A male enthusiast or devotee; a male who is very fond of or devoted to a specified kind of thing. (Used as the last element of a compound.)
- A person, usually male, who has duties or skills associated with a specified thing. (Used as the last element of a compound.)
- A person, usually male, who can fulfill one's requirements with regard to a specified matter.
- A male who belongs to a particular group: an employee, a student or alumnus, a representative, etc.
- An adult male servant.
- A vassal; a subject.
- A piece or token used in board games such as chess.
- Used to refer to oneself or one's group: I, we; construed in the third person.
- A term of familiar address often implying on the part of the speaker some degree of authority, impatience, or haste.
- A friendly term of address usually reserved for other adult males.
- A player on whom another is playing, with the intent of limiting their attacking impact.
- A person trained in ninjutsu, especially one used for espionage, assassination, and other tasks requiring stealth during Japan's shogunate period.
- A person considered similarly skillful to the historical ninja, especially in covert or stealthy operation.
- A person considered to look like the historical ninja in some way, including (Mongolia) amateur private miners.
- To act or move like a ninja, particularly with regard to a combination of speed, power, and stealth.
- To claim an item through abuse of game mechanics.
- Of or related to ninjas in their various senses.
- To appropriate something (before someone else does).
- To displace something, or take precedence over something.
- To secure (land, etc.) by the right of preemption.
- To make a preemptive bid at bridge.