Head of Government in trip, with European for support (9)
I believe the answer is:
ridgepole
'support' is the definition.
(ridgepole is a kind of support)
'head of government in trip with european' is the wordplay.
'head of' says to take the initial letters.
'in' is an insertion indicator.
'trip' becomes 'ride' (I've seen this before).
'with' says to put letters next to each other.
'european' becomes 'pole' (someone from Poland).
The first letter of 'government' is 'g'.
'g' placed into 'ride' is 'ridge'.
'ridge'+'pole'='RIDGEPOLE'
'for' acts as a link.
(Other definitions for ridgepole that I've seen before include "Horizontal member in a long tent" , "Top strut of tent" .)