Some art at expensive gallery (4)
I believe the answer is:
tate
'gallery' is the definition.
(Tate Modern, Tate Britain etc)
'some art at expensive' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'TATE' is hidden in the letters of 'art at expensive'.
(Other definitions for tate that I've seen before include "famous art gallery beside London's Thames" , "- - Modern: art gallery" , "Art gallery in London, Liverpool and St Ives" , "Gallery (or two!)" , "Art gallery benefactor" .)