Difficulty replacing our belt (7)
I believe the answer is:
trouble
'difficulty' is the definition.
(trouble is a kind of difficulty)
'replacing our belt' is the wordplay.
'replacing' is an anagram indicator (placing again).
'our'+'belt'='ourbelt'
'ourbelt' is an anagram of 'TROUBLE'.
(Other definitions for trouble that I've seen before include "Difficulty; public disorder" , "Difficulty or inconvenience" , "Difficulty; cause distress to" , "Hassle" , "Distress - concern - effort" .)