Go up for a broadcast full of cold (6)
I believe the answer is:
ascend
'go up' is the definition.
('ascend' can be a synonym of 'go up')
'a broadcast full of cold' is the wordplay.
'broadcast' becomes 'send' ('send' can be a synonym of 'broadcast'**).
'full of' means one lot of letters goes inside another.
'cold' becomes 'c' (eg on taps).
'send' going around 'c' is 'scend'.
'a'+'scend'='ASCEND'
'for' acts as a link.
(Other definitions for ascend that I've seen before include "rise in status" , "shift to a higher plane" , "Gain height" , "Gain altitude" , "Dances (anag.)" .)