British want to protect the old scoundrel (10)
I believe the answer is:
blackguard
'old scoundrel' is the definition.
('blackguard' is a dated term for a scoundrel)
'british want to protect' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'want' becomes 'lack' (synonyms).
'to protect' becomes 'guard' (guarding is a kind of protecting).
'b'+'lack'+'guard'='BLACKGUARD'
'the' acts as a link.
(Other definitions for blackguard that I've seen before include "miscreant" , "Villain" , "Dishonourable man" , "Contemptible scoundrel" , "Cad" .)