Flavour of snack originally found in gallery (5)
I believe the answer is:
taste
'flavour' is the definition.
(I've seen this before)
'snack originally found in gallery' is the wordplay.
'originally' indicates taking the first letters.
'found in' indicates putting letters inside.
'gallery' becomes 'tate' (Tate Modern, Tate Britain etc).
The initial letter of 'snack' is 's'.
's' going within 'tate' is 'TASTE'.
'of' is the link.
(Other definitions for taste that I've seen before include "To eat sparingly" , "Experience - discrimination" , "one of the 4 [SENSE] s" , "Delicacy" , "Refinement or flavour" .)