Chuck and Mike gate-crashing party in NI (4)
I believe the answer is:
dump
'chuck' is the definition.
(thesaurus)
'mike gate-crashing party in ni' is the wordplay.
'mike' becomes 'M' (phonetic alphabet: alpha, bravo, charlie etc.).
'gate-crashing' is an insertion indicator (letters gate-crash into the word).
'party in ni' becomes 'DUP' (Democratic Unionist Party of Northern Ireland).
'm' going inside 'dup' is 'DUMP'.
'and' is the link.
(Other definitions for dump that I've seen before include "waste ground?" , "Jettison; (rubbish) tip" , "Repository for rubbish etc" , "Public rubbish tip" , "Unload" .)