The most common and most likely answer to this crossword clue is the 6 letter word RINGER
I've seen this crossword clue in The Times
R
I
N
G
E
R
More clues leading to the result RINGER
- Campanologist’s double?
- Suspect racehorse and call on Queen
- Some player in Germany who shouldn’t be in the team?
- Phone twin
- Call on important lady, one who knows the ropes?
- Impostor to try to make attempt at phoning Buckingham Palace?
- Double Gloucester in German houses? +
- Double bell?
- Church musician, one who shouldn’t be playing?
- One who calls ‘Double’?
Buddy explains!

The straight part
We know that "Suspect racehorse" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case suspect racehorse = ringer.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 RINGER mean?
RINGER noun- Someone who rings, especially a bell ringer.
- A crowbar.
- (games) In the game of horseshoes, the event of the horseshoe landing around the pole.
- (games) A game of marbles where players attempt to knock each other's marbles out of a ring drawn on the ground.
- A ringer T-shirt.
- A person highly proficient at a skill or sport who is brought in, often fraudulently, to supplement a team.
- A horse fraudulently entered in a race using the name of another horse.
- A person, animal, or entity which resembles another so closely as to be taken for the other, now usually in the phrase dead ringer.
- A fraudulently cloned motor vehicle.
- A top performer.
- The champion shearer of a shearing shed.
- A stockman, a cowboy.
- Any person or thing that is fraudulent; a fake or impostor.
- (in combination) An officer having the specified number of rings (denoting rank) on the uniform sleeve.