Host politician, European, in centre (7)
I believe the answer is:
compere
'host' is the definition.
(compere is a kind of host)
'politician european in centre' is the wordplay.
'politician' becomes 'mp' (Member of Parliament).
'european' becomes 'E' (abbreviation e.g. EU).
'in' means one lot of letters goes inside another.
'centre' becomes 'core' (core is a kind of centre).
'mp'+'e'='mpe'
'mpe' placed within 'core' is 'COMPERE'.
(Other definitions for compere that I've seen before include "TV presenter?" , "host show" , "M.C." , "Master of ceremonies" , "(Male) show introducer" .)