The most common and most likely answer to this crossword clue is the 5 letter word AMIGO
I've seen this crossword clue in The Times
A
M
I
G
O
More clues leading to the result AMIGO
- Contrary old soldier, mother's mate from abroad
- A short time entertaining one good chum abroad
- A warplane over China
- Friend’s note written during a match
- Foreign ally questioning whether he can proceed?
- In the morning I leave China
- A motorway turn in China
- Friend has a turn crossing motorway
- Spanish friend to work with a French one
- Before midday I leave to find companion
Buddy explains!

The straight part
We know that "companion" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case companion = amigo.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 AMIGO mean?
AMIGO noun- Friend
- (chiefly California) Mexican
- A native of the Philippines who was friendly toward the Spanish.