Come in to see Aberdeen terriers? Not entirely (5)
I believe the answer is:
enter
'come in' is the definition.
(synonyms)
'to see aberdeen terriers? not entirely' is the wordplay.
'not entirely' indicates a hidden word.
'ENTER' is hidden within 'to aberdeen terriers'.
(Other definitions for enter that I've seen before include "Introduce" , "Fruit drink" , "Enroll, sign up" , "Register (as a competitor)" , "Make a record of" .)