Check someone for suitability (3)
I believe the answer is:
vet
'check someone for suitability' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for vet that I've seen before include "Examine carefully - might one help a lame duck?" , "Screen" , "Check someone for suitability" , "animal doctor to > investigate" , "'Examine this doctor, in short (3)'" .)