Head off state torture's introduction (5)
I believe the answer is:
avert
'head off' is the definition.
('avert' can be a synonym of 'head off')
'state torture's introduction' is the wordplay.
'state' becomes 'aver' (I've seen this before**).
'introduction' suggests taking the first letters.
The initial letter of 'tortures' is 't'.
'aver'+'t'='AVERT'
(Other definitions for avert that I've seen before include "Fend off" , "Obviate" , "Prevent from occurring" , "Turn away from, say gaze" , "Turn away (ones eyes)" .)