Broadcast drunk? Beyond question (8)
I believe the answer is:
airtight
'beyond question' is the definition.
(I've seen this before)
'broadcast drunk?' is the wordplay.
'broadcast' becomes 'air' (to air on TV).
'drunk?' becomes 'tight' (slang term).
'air'+'tight'='AIRTIGHT'
(Other definitions for airtight that I've seen before include "(Of a defence) having no weaknesses" , "securely sealed" , "Firmly closed" , "With no opening" , "beyond question" .)