Clash with politician blocking international law (6)
I believe the answer is:
impact
'clash' is the definition.
(thesaurus)
'politician blocking international law' is the wordplay.
'politician' becomes 'MP' (Member of Parliament).
'blocking' means one lot of letters goes inside another.
'international' becomes 'i' (abbreviation eg in IMF).
'law' becomes 'act' (I've seen this before).
'i'+'act'='iact'
'mp' inserted within 'iact' is 'IMPACT'.
'with' is the link.
(Other definitions for impact that I've seen before include "Repercussion" , "Strong effect" , "Marked effect or influence" , "Result" , "Repercussions" .)