British want to protect the blighter (10)
I believe the answer is:
blackguard
'the blighter' is the definition.
'british want to protect' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'want' becomes 'lack' ('lack' can be a synonym of 'want').
'to protect' becomes 'guard' (guarding is a kind of protecting).
'b'+'lack'+'guard'='BLACKGUARD'
(Other definitions for blackguard that I've seen before include "miscreant" , "Cad" , "Contemptible scoundrel" , "rogue" , "Villain" .)