Animal doctor has a large domestic (5)
I believe the answer is:
valet
'domestic' is the definition.
(type of domestic servant)
'animal doctor has a large' is the wordplay.
'animal doctor' becomes 'vet' (I've seen this before).
'has' is an insertion indicator.
'a large' becomes 'al' (I've seen this in other clues).
'vet' placed around 'al' is 'VALET'.
(Other definitions for valet that I've seen before include "Batman" , "Personal servant" , "Man's manservant" , "Man's personal attendant" , "Gentleman's attendant" .)