Host politician, English, in centre (7)
I believe the answer is:
'host' is the definition.
(host of an event)
'politician english in centre' is the wordplay.
'politician' becomes 'mp' (Member of Parliament).
'english' becomes 'E' (abbreviation as in OED).
'in' is an insertion indicator.
'centre' becomes 'core' (core can mean something's centre).
'mp'+'e'='mpe'
'mpe' going within 'core' is 'COMPERE'.
(Other definitions for compere that I've seen before include "TV presenter?" , "Master of ceremonies" , "(Male) show introducer" , "host show" , "M.C." .)