Protection for redhead in love affair (6)
I believe the answer is:
armour
'protection' is the definition.
(armour is a kind of protection)
'redhead in love affair' is the wordplay.
'redhead' becomes 'r' (the head/first letter of 'red').
'in' indicates putting letters inside.
'love affair' becomes 'amour' (I've seen this before).
'r' put within 'amour' is 'ARMOUR'.
'for' is the link.
(Other definitions for armour that I've seen before include "Protective clothing" , "Suit of mail" , "Body plate" , "Soldier's body protection" , "Metal or other protective plating for body" .)