More compact shopping centre in London area works, essentially (7)
I believe the answer is:
smaller
'more compact' is the definition.
(I've seen this in another clue)
'shopping centre in london area works essentially' is the wordplay.
'shopping centre' becomes 'mall' (a mall is a large shopping complex).
'in' means one lot of letters goes inside another.
'london area' becomes 'SE' (abbreviation for South East).
'works' becomes 'art' (I've seen this before).
'essentially' means to look at the middle letters.
The middle letter of 'art' is 'r'.
'mall' placed into 'se' is 'smalle'.
'smalle'+'r'='SMALLER'
(Other definitions for smaller that I've seen before include "Not as big as" , "More diminutive" , "Less extensive" , "Sell ram (anag.)" .)