Record: wine gradually diminished (7)
I believe the answer is:
tapered
'gradually diminished' is the definition.
(I've seen this before)
'record wine' is the wordplay.
'record' becomes 'tape record' (synonyms).
'wine' becomes 'red' (red is a type of wine).
'tape'+'red'='TAPERED'
(Other definitions for tapered that I've seen before include "Narrowing towards one end" , "Gradually narrowing" , "Narrowed by red tape" , "Gradually diminished" , "Predate (anag)" .)