Old Judge in broadcast knocked back wine (5)
I believe the answer is:
rioja
'wine' is the definition.
(Rioja is an example)
'old judge in broadcast knocked back' is the wordplay.
'old' becomes 'o' (abbreviation as in OT - Old Testament).
'judge' becomes 'J' (abbreviation for judge).
'in' indicates putting letters inside.
'broadcast' becomes 'air' (to air on TV).
'knocked back' says the letters should be written backwards.
'air' written backwards gives 'ria'.
'o'+'j'='oj'
'oj' put into 'ria' is 'RIOJA'.
(Other definitions for rioja that I've seen before include "Spanish wine type" , "Open space (ancient Greek)" , "kind of red" , "Spanish red wine" , "Spanish drink" .)