Attempt to arrest old right-winger (4)
I believe the answer is:
tory
'right-winger' is the definition.
(Tory is an example)
'attempt to arrest old' is the wordplay.
'attempt to' becomes 'try' (I've seen this in other clues).
'arrest' is an insertion indicator.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'try' enclosing 'o' is 'TORY'.
(Other definitions for tory that I've seen before include "Opponent of 8 Down and 14 Across, partner of 14 Down?" , "English Conservative politician or Donegal island" , "Politician; tyro (anag.)" , "blue" , "type on right? Yes" .)