A dry, unopened, alternative to cider (5)
I believe the answer is:
perry
'alternative to cider' is the definition.
I can't tell whether this defines the answer.
'a dry unopened' is the wordplay.
'a' becomes 'per' (eg 'one a day' means 'one per day').
'unopened' means to remove the first letter (without opening letter).
'dry' with its initial letter taken away is 'ry'.
'per'+'ry'='PERRY'
Can you help me to learn more?
(Other definitions for perry that I've seen before include "Pear cider" , "-- Como, singer" , "Alcoholic pear drink" , "Alcoholic fruit drink" , "Pear wine" .)