Politician in government to mess up (6)
I believe the answer is:
rumple
'mess up' is the definition.
('rumple' can be a synonym of 'mess up')
'politician in government' is the wordplay.
'politician' becomes 'mp'.
'in' is an insertion indicator.
'government' becomes 'rule' (I've seen this before).
'mp' placed inside 'rule' is 'RUMPLE'.
'to' acts as a link.
(Other definitions for rumple that I've seen before include "disorder" , "Make untidy, say clothes" , "Dishevel, ruffle" , "Disturb the smoothness" , "Make uneven or wrinkled" .)