Coke and resin oil supplier in London area (10)
I believe the answer is:
camberwell
'london area' is the definition.
(area of South London)
'coke and resin oil supplier' is the wordplay.
'coke' becomes 'C' (synonyms).
'and' means one lot of letters go next to another.
'resin' becomes 'amber' (amber is a kind of resin).
'oil supplier' becomes 'well' (oil well).
'c'+'amber'+'well'='CAMBERWELL'
'in' is the link.
(Other definitions for camberwell that I've seen before include "South London district" , "Part of South London" .)