Staff outside gallery took turns (7)
I believe the answer is:
rotated
'took turns' is the definition.
(rotating is a kind of taking turns)
'staff outside gallery' is the wordplay.
'staff' becomes 'rod' (I've seen this before).
'outside' indicates putting letters inside.
'gallery' becomes 'tate' (I've seen this before).
'rod' enclosing 'tate' is 'ROTATED'.
(Other definitions for rotated that I've seen before include "Turner did?" , "Spun" , "took part in revolution" , "Turned round" , "Had spin" .)