Cat doc (3)
I believe the answer is:
vet
'cat doc' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for vet that I've seen before include "'Examine this doctor, in short (3)'" , "solider once" , "animal doctor to > investigate" , "'Animal doctor, in short (3)'" , "Check someone for suitability" .)