Watch from gallery, following instructions (8)
I believe the answer is:
spectate
'watch' is the definition.
(I know that spectate is a kind of the watch)
'gallery following instructions' is the wordplay.
'gallery' becomes 'tate' (Tate Modern, Tate Britain etc).
'following' is a charade indicator (letters next to each other).
'instructions' becomes 'spec' (I've seen this before).
'tate' after 'spec' is 'SPECTATE'.
'from' acts as a link.
(Other definitions for spectate that I've seen before include "Look on (at a match)" , "Watch (at sports event)" , "Be a viewer, at a sports event perhaps" , "Watch (a game, etc)" , "Watch (eg, a game)" .)