Staff outside art gallery took turns (7)
I believe the answer is:
rotated
'took turns' is the definition.
(rotating is a kind of taking turns)
'staff outside art gallery' is the wordplay.
'staff' becomes 'rod' (both can mean a stick or cane).
'outside' indicates putting letters inside (some letters go outside others).
'art gallery' becomes 'tate' (Tate Modern, Tate Britain etc).
'rod' enclosing 'tate' is 'ROTATED'.
(Other definitions for rotated that I've seen before include "Turned in a circle around an axis" , "took part in revolution" , "Turner did?" , "Turned round" , "Spun" .)