London art gallery (4)
I believe the answer is:
'london art gallery' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for tate that I've seen before include "Gallery (or two!)" , "Art gallery founded by sugar magnate" , "Maurice - - , cricketer 1895-1956" , "- - Modern: art gallery" , "Well-known London art gallery" .)