More plots developed surrounding one big city (10)
I believe the answer is:
metropolis
'big city' is the definition.
(I've seen this before)
'more plots developed surrounding one' is the wordplay.
'developed' indicates anagramming the letters.
'surrounding' indicates putting letters inside.
'one' becomes 'i' (Roman numeral).
'more'+'plots'='moreplots'
'moreplots' is an anagram of 'metropols'.
'metropols' going around 'i' is 'METROPOLIS'.
(Other definitions for metropolis that I've seen before include "Big city" , "Very large city" , "early film" , "Chief city" , "Expressionist movie" .)