Troublemaker on broadcast intended being heartless, creating harm (10)
I believe the answer is:
impairment
'harm' is the definition.
(I know that harm can be written as impairment)
'troublemaker on broadcast intended being heartless' is the wordplay.
'troublemaker' becomes 'imp' (I've seen this in another clue).
'on broadcast' becomes 'air' (to air on TV. I am not sure about the 'on' bit.).
'intended' becomes 'meant' (to mean something is to intend it).
'being heartless' says to hollow out the word (remove centre letters).
'meant' with its centre removed is 'ment'.
'imp'+'air'+'ment'='IMPAIRMENT'
'creating' acts as a link.
(Other definitions for impairment that I've seen before include "Disability" , "Weakening, damage" , "Injury" .)