Writer backed British ship in trade restriction (7)
I believe the answer is:
embargo
'trade restriction' is the definition.
(I've seen this in another clue)
'writer backed british ship' is the wordplay.
'writer' becomes 'me' (the person who wrote the clues).
'backed' says the letters should be written backwards.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'ship' becomes 'argo' (I've seen this before).
'me' reversed gives 'em'.
'em'+'b'+'argo'='EMBARGO'
'in' is the link.
(Other definitions for embargo that I've seen before include "Prevent publication" , "Commercial ban" , "Ban or restraint on trade" , "Government trade ban" , "Government order imposing a trade barrier" .)