Attempt to protect old politician (4)
I believe the answer is:
tory
'politician' is the definition.
(I've seen this before)
'attempt to protect old' is the wordplay.
'attempt' becomes 'try' (I've seen this before).
'to protect' indicates putting letters inside.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'try' going around 'o' is 'TORY'.
(Other definitions for tory that I've seen before include "type on right? Yes" , "blue" , "Opponent of 8 Down and 14 Across, partner of 14 Down?" , "Politician; tyro (anag.)" , "A British Conservative" .)