First bit of terrible wine no good for sampling (7)
I believe the answer is:
tasting
'sampling' is the definition.
('taste' can be a synonym of 'sample')
'first bit of terrible wine no good' is the wordplay.
'first bit of terrible' becomes 't' (1st letter of 'terrible').
'wine' becomes 'asti' (Italian wine).
'no good' becomes 'ng' (abbreviation).
't'+'asti'+'ng'='TASTING'
'for' acts as a link.
(Other definitions for tasting that I've seen before include "Sampling (food)" , "event with wine" , "Savouring" .)