Star seen in massive gallery (4)
I believe the answer is:
vega
'star' is the definition.
(Vega is an example)
'in massive gallery' is the wordplay.
'in' says the answer is hidden in the clue.
'VEGA' is hidden in the letters of 'massive gallery'.
'seen' acts as a link.
(Other definitions for vega that I've seen before include "Gave turn to a star" , "heavenly body" , "Bright star of constellation Lyra" , "Fifth brightest star" , "Brightest star of constellation Lyra" .)