Hang in Pisa gallery (3)
I believe the answer is:
sag
'hang' is the definition.
(I've seen this in another clue)
'in pisa gallery' is the wordplay.
'in' indicates the answer is hidden within the clue.
'SAG' is hidden within 'pisa gallery'.
(Other definitions for sag that I've seen before include "Spinach as used in Indian cookery" , "fall" , "Fail to retain interest" , "Give way under pressure" , "Hang down loosely" .)