Garment for British parasite (6)
I believe the answer is:
blouse
'garment' is the definition.
(I know that blouse is a type of garment)
'british parasite' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in BBC).
'parasite' becomes 'louse' (type of parasitic insect).
'b'+'louse'='BLOUSE'
'for' acts as a link.
(Other definitions for blouse that I've seen before include "Lady's garment" , "Shirt-like garment for women" , "Top garment - so blue (anag)" , "Female garment" , "Obelus (anag) - buttoned top" .)