Small taste? Not small, big (5)
I believe the answer is:
ample
'big' is the definition.
(similar in meaning)
'small taste? not small' is the wordplay.
'small taste?' becomes 'sample' (I've seen this in another clue).
'not' is a deletion indicator.
'small' becomes 's' (abbreviation - e.g. clothes size).
'sample' with 's' removed is 'AMPLE'.
(Other definitions for ample that I've seen before include "Fully enough" , "Bulky" , "Quite sufficient, more than enough" , "Copious - abundant" , "Adequate" .)