Introducing nothing to attempt to be conservative (4)
I believe the answer is:
tory
'be conservative' is the definition.
(informal term for a Conservative Party member)
'introducing nothing to attempt' is the wordplay.
'introducing' is an insertion indicator (some letters introduced or inserted into others).
'nothing' becomes 'O' (looks like zero - 0).
'to attempt' becomes 'try' (synonyms).
'o' placed inside 'try' is 'TORY'.
'to' is the link.
(Other definitions for tory that I've seen before include "blue" , "type on right? Yes" , "English Conservative politician or Donegal island" , "A British Conservative" , "Traditionalist" .)