Turning round, it’s always unable to stay still (7)
I believe the answer is:
restive
'unable to stay still' is the definition.
(I've seen this before)
'turning round it's always' is the wordplay.
'turning' says the letters should be written in reverse.
'round' is an insertion indicator.
'always' becomes 'ever' ('ever' can be a synonym of 'always').
'its' put inside 'ever' is 'evitser'.
'evitser' backwards is 'RESTIVE'.
(Other definitions for restive that I've seen before include "Resisting control, nervous or impatient" , "Unsettled" , "Unable to keep still" , "Impatient of authority" , "Impatient - jumpy" .)