A huge development in a city (5)
I believe the answer is:
hague
'a city' is the definition.
Both the answer and definition are singular nouns.
Perhaps they are linked in a way I don't understand?
'a huge development in' is the wordplay.
'development' indicates anagramming the letters.
'in' is an insertion indicator.
'huge' is an anagram of 'hgue'.
'a' going into 'hgue' is 'HAGUE'.
Can you help me to learn more?
(Other definitions for hague that I've seen before include "politician" , "The city of the International Court of Justice" , "William -, former Conservative leader" , "The ..... is the Netherlands seat of government" .)