Drink quietly, repeatedly, at home, gaining weight (4,3)
I believe the answer is:
pink gin
'drink' is the definition.
(I've seen this before)
'quietly repeatedly at home gaining weight' is the wordplay.
'quietly' becomes 'p' (p for piano and quiet).
'repeatedly' indicates the doubling of some letters.
'at home' becomes 'in' (similar in meaning).
'gaining' is an insertion indicator.
'weight' becomes 'kg'.
'in' duplicated is 'inin'.
'inin' placed around 'kg' is 'inkgin'.
'p'+'inkgin'='PINK GIN'
(Other definitions for pink gin that I've seen before include "Kingpin (anag.)" , "Geneva and bitters" , "Drink with angostura bitters" , "Alcoholic drink" , "Drink with 9" .)