Torque (7)
I believe the answer is:
torsion
'torque' is the definition.
(I know that torque can be written as torsion)
This is all the clue.
(Other definitions for torsion that I've seen before include "twist" , "Twisting force" , "Process of twisting" , "Twisted position - no riots (anag)" , "Tortuous and twisted shape or position" .)