Offer of support also broadcast (8)
I believe the answer is:
proposal
'offer' is the definition.
(proposal is a kind of offer)
'support also broadcast' is the wordplay.
'support' becomes 'prop' (prop is a kind of support).
'broadcast' indicates anagramming the letters.
'also' with letters rearranged gives 'osal'.
'prop'+'osal'='PROPOSAL'
'of' is the link.
(Other definitions for proposal that I've seen before include "Kind of offer, perhaps of marriage" , "Suggestion put forward for consideration" , "A suggestion, perhaps of marriage" , "put before the union?" , "a match might be arranged?" .)