Bus travelling north from city, heading for B&Q that's on the outskirts (6)
I believe the answer is:
suburb
'outskirts' is the definition.
(thesaurus)
'bus travelling north from city heading for bq that's on' is the wordplay.
'travelling north' says the letters should be written in reverse (in a down clue, letters go up).
'from' means one lot of letters go next to another.
'city' becomes 'ur' (ancient Sumerian city state).
'heading for' suggests taking the first letters.
'that's on' means one lot of letters go next to another.
The first letter of 'bq' is 'b'.
'bus' reversed gives 'sub'.
'sub'+'ur'+'b'='SUBURB'
'the' acts as a link.
(Other definitions for suburb that I've seen before include "Area on the periphery of a city" , "Present (bill); melt down (fat)" , "Residential city area" , "Area on the outskirts of a city" , "Residential district on the outskirts of a city" .)