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' says the answer is hidden in the clue.
'ENTER' can be found hidden inside '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" .)