Nothing in Lancashire town demolished (4)
I believe the answer is:
nowt
'nothing in lancashire' is the definition.
(northern dialect term meaning 'nothing')
'town demolished' is the wordplay.
'demolished' indicates an anagram.
'town' anagrammed gives 'NOWT'.
(Other definitions for nowt that I've seen before include "FA" , "Town (anag.)" , "0" , "Northern 15 [NIX]" , "(In Yorkshire) nothing!" .)