Damage independent politician before broadcast (6)
I believe the answer is:
impair
'damage' is the definition.
(impairing is a kind of damaging)
'independent politician before broadcast' is the wordplay.
'independent' becomes 'i'.
'politician' becomes 'mp'.
'before' means one lot of letters go next to another.
'broadcast' becomes 'air' ('air' can be a synonym of 'broadcast').
'i'+'mp'+'air'='IMPAIR'
(Other definitions for impair that I've seen before include "Damage or handicap" , "Hinder" , "blunt" , "Damage or injure" , "Courteous man (colloq.)" .)