Damage rascal with broadcast (6)
I believe the answer is:
impair
'damage' is the definition.
(impairing is a kind of damaging)
'rascal with broadcast' is the wordplay.
'rascal' becomes 'imp' (synonyms).
'with' means one lot of letters go next to another.
'broadcast' becomes 'air' (to air on TV).
'imp'+'air'='IMPAIR'
(Other definitions for impair that I've seen before include "Cause weakening of, damage" , "Hobble" , "'Mar, damage (6)'" , "Hinder" , "Damage or injure" .)