Service station imports British rubbish (7)
I believe the answer is:
garbage
'rubbish' is the definition.
(both can mean refuse or trash)
'service station imports british' is the wordplay.
'service station' becomes 'garage' (I can't justify this - if you can you should believe this answer much more).
'imports' means one lot of letters goes inside another (inserted letters are imported).
'british' becomes 'b' (abbreviation e.g. in BBC).
'garage' enclosing 'b' is 'GARBAGE'.
Can you help me to learn more?
(Other definitions for garbage that I've seen before include "Unwanted stuff" , "A beggar? - that may be rubbish" , "Nonsense!" , "Worthless matter" , "hot air" .)