In London area round the bend (7)
I believe the answer is:
popular
'in' is the definition.
'london area round the bend' is the wordplay.
'london area' becomes 'poplar' (I've seen this before).
'round' indicates putting letters inside.
'the bend' becomes 'U' (a U-bend is a kind of bend - pipe under sink).
'poplar' placed around 'u' is 'POPULAR'.
(Other definitions for popular that I've seen before include "In demand" , "having many fans" , "Well-liked" , "Widely admired" , "In general favour" .)