Announce politician in real time (7)
I believe the answer is:
trumpet
'announce' is the definition.
(both can mean to proclaim)
'politician in real time' is the wordplay.
'politician' becomes 'mp' (Member of Parliament).
'in' indicates putting letters inside.
'real' becomes 'true' (synonyms).
'time' becomes 't' (abbreviation).
'mp' placed into 'true' is 'trumpe'.
'trumpe'+'t'='TRUMPET'
(Other definitions for trumpet that I've seen before include "beastly noise" , "Horn" , "Brass wind instrument" , "brassy type" , "Loudly sound - instrument" .)