Chap is after part of London common (9)
I believe the answer is:
hackneyed
'common' is the definition.
(thesaurus)
'chap is after part of london' is the wordplay.
'chap' becomes 'Ed' (short for Edward).
'is after' says to put letters next to each other.
'part of london' becomes 'hackney'.
'ed' after 'hackney' is 'HACKNEYED'.
(Other definitions for hackneyed that I've seen before include "using familiar phraseology?" , "Overfamiliar through overuse" , "corny" , "Trite, stale" , "stock" .)