She’s a no-good, knocking back drink (6)
I believe the answer is:
angela
'she's' is the definition.
(I've seen this before)
'a no-good knocking back drink' is the wordplay.
'no' becomes 'n' (common abbreviation).
'good' becomes 'g' (abbreviation).
'knocking back' says the letters should be written backwards.
'drink' becomes 'ale' (ale is a kind of drink**).
'ale' back-to-front is 'ela'.
'a'+'n'+'g'+'ela'='ANGELA'
(Other definitions for angela that I've seen before include "woman" , "- Gheorghiu, Romanian soprano" , ". . . Lansbury (actress)" , "Frau Merkel" , "Girl's name" .)