Dry in excellent cold storage area? (5)
I believe the answer is:
attic
'storage area?' is the definition.
(an attic may be used as storage space)
'dry in excellent cold' is the wordplay.
'dry' becomes 'tt' (short for teetotal - no alcohol).
'in' means one lot of letters goes inside another.
'excellent' becomes 'ai' (resembles 'A1', old-fashioned term for excellent).
'cold' becomes 'c' (eg on taps).
'tt' placed within 'ai' is 'atti'.
'atti'+'c'='ATTIC'
(Other definitions for attic that I've seen before include "Top apartment" , "Greek - upper room" , "Athenian Greek" , "Ancient Greek dialect - top room" , "Room at the top of a house" .)