Refinement seen originally in gallery (5)
I believe the answer is:
taste
'refinement' is the definition.
(I've seen this before)
'seen originally in gallery' is the wordplay.
'originally' says to take the initial letters.
'in' is an insertion indicator.
'gallery' becomes 'tate' (Tate Modern, Tate Britain etc).
The first letter of 'seen' is 's'.
's' inserted inside 'tate' is 'TASTE'.
(Other definitions for taste that I've seen before include "Sensation of flavour" , "Judgment" , "Experience - discrimination" , "Discrimination - a sense" , "Delicate discrimination" .)