Insane guys and Tory leader in action (8)
I believe the answer is:
demented
'insane' is the definition.
('demented' can be similar in meaning to 'insane')
'guys and tory leader in action' is the wordplay.
'guys' becomes 'men'.
'and' means one lot of letters go next to another.
'tory leader' becomes 't' (I've seen this in other clues).
'in' indicates putting letters inside.
'action' becomes 'deed' (deed is a kind of action).
'men'+'t'='ment'
'ment' going inside 'deed' is 'DEMENTED'.
(Other definitions for demented that I've seen before include "Crazy, insane" , "Deranged, crazy" , "Out of one's mind" , "Driven mad, crazy" , "Wild, irrational" .)