Do alter tight garment (7)
I believe the answer is:
leotard
'garment' is the definition.
(I've seen this before)
'do alter tight' is the wordplay.
'tight' indicates an anagram (tight can mean drunk).
'do'+'alter'='doalter'
'doalter' anagrammed gives 'LEOTARD'.
(Other definitions for leotard that I've seen before include "One-piece garment worn by acrobat" , "Dance/exercise garment" , "Stretchy one-piece garment" , "Close-fitting garment worn by dancers" , "Gymnast's tight costume" .)