Smack son in art gallery (5)
I believe the answer is:
taste
'smack' is the definition.
(to smack of something is to taste of it)
'son in art gallery' is the wordplay.
'son' becomes 's' (genealogical abbreviation for son).
'in' indicates putting letters inside.
'art gallery' becomes 'tate' (Tate Modern, Tate Britain etc).
's' going inside 'tate' is 'TASTE'.
(Other definitions for taste that I've seen before include "one of the 4 [SENSE] s" , "Predilection" , "to eat in small amounts" , "Little bit" , "Take mouthful" .)