Large towns with 101 connections (6)
I believe the answer is:
cities
'large towns' is the definition.
'with 101 connections' is the wordplay.
'with' is a charade indicator (letters next to each other).
'101' becomes 'CI' (roman numerals).
'connections' becomes 'ties' (tie is a kind of connection).
'ci' next to 'ties' is 'CITIES'.
(Other definitions for cities that I've seen before include "Densely-populated urban areas" , "urban centres" , "Densely populated urban areas" , "Large Urban areas" , "Large conurbations" .)