Use bad language about alien brought up in Jersey (7)
I believe the answer is:
sweater
'jersey' is the definition.
(I've seen this before)
'use bad language about alien brought up' is the wordplay.
'use bad language' becomes 'swear' (I've seen this before).
'about' is an insertion indicator.
'alien' becomes 'et' (extra terrestrial).
'brought up' is a reversal indicator (down clues only).
'et' written backwards gives 'te'.
'swear' placed around 'te' is 'SWEATER'.
'in' is the link.
(Other definitions for sweater that I've seen before include "Jersey may become" , "mugger once" , "A present from Mum!" , "Woolly" , "Warm garment" .)