Beastly doctor? (3)
I believe the answer is:
vet
'doctor?' is the definition.
(I know that vet is a more specific form of doctor)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for vet that I've seen before include "Experienced" , "'Examine this doctor, in short (3)'" , "Check someone for suitability" , "A diminutive animal doctor" , "Scrutinise" .)