To sort out the coppers can be fun! (5)
I believe the answer is:
sport
'fun' is the definition.
(synonyms)
'to sort out the coppers' is the wordplay.
'out' means one lot of letters goes inside another.
'the coppers' becomes 'p'.
'sort' enclosing 'p' is 'SPORT'.
'can be' is the link.
(Other definitions for sport that I've seen before include "Eg, football; fun" , "Fun in ports" , "Show off" , "Games" , "Fun; wear" .)