Must hit balls with purpose when being broadcast? (4)

I believe the answer is:
need
'must' is the definition.
(synonyms)
'hit balls with purpose when being broadcast?' is the wordplay.
I cannot really understand how this works, but
'balls' could be 'ed' (I've seen this in other clues) and 'ed' is present in the answer.
The remaining letters 'ne' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for need that I've seen before include "Desideratum" , "Call" , "'miss'" , "A condition" , "Lack - demand" .)
