To put it briefly, knock around the city area (5)
I believe the answer is:
recap
'to put it briefly knock around the city area' is the definition.
I can't tell whether this definition defines the answer.
'knock around the city area' is the wordplay.
'knock' becomes 'rap' (synonyms).
'around' is an insertion indicator.
'the city area' becomes 'EC' (EC is a London postcode area).
'rap' enclosing 'ec' is 'RECAP'.
Can you help me to learn more?
(Other definitions for recap that I've seen before include "Repeat of main points" , "Go over again in the mind" , "Summary (abbr.)" , "Go over study material again" , "sum everything up" .)