Restraint limiting attempt to turn at the same time (8)
I believe the answer is:
together
'at the same time' is the definition.
('together' can be a synonym of 'at the same time')
'restraint limiting attempt to turn' is the wordplay.
'restraint' becomes 'tether' (tether is a kind of restraint**).
'limiting' indicates putting letters inside.
'attempt' becomes 'go' (go is a kind of attempt).
'to turn' says the letters should be written backwards.
'go' in reverse letter order is 'og'.
'tether' enclosing 'og' is 'TOGETHER'.
(Other definitions for together that I've seen before include "Concertedly" , "as a group" , "in league" , "Level-headed" , "On the trot" .)