What’s sweet moment with girls (8)
I believe the answer is:
molasses
'what's sweet' is the definition.
(I've seen this before)
'moment with girls' is the wordplay.
'moment' becomes 'mo' (as in 'just a mo').
'with' is a charade indicator (letters next to each other).
'girls' becomes 'lasses' (lass can informally mean a girl).
'mo'+'lasses'='MOLASSES'
(Other definitions for molasses that I've seen before include "Dark syrup extracted from sugar cane" , "sticky food" , "Slow runner" , "Thick syrup extracted from sugar cane" , "Thick treacle left over after refining raw sugar" .)