Sports event official's broadcast from another planet (7)
I believe the answer is:
martial
'from another planet' is the definition.
(martial can mean relating to Mars)
'sports event official's broadcast' is the wordplay.
'sports event official' becomes 'marshal' (I've seen this before).
'broadcast' shows a homophone (sound like) (how the word might sound on the radio or TV).
'marshal' sounds like 'MARTIAL'.
(Other definitions for martial that I've seen before include "Warlike; Roman poet" , "Relating to the armed forces" , "associated with arts and law" , "Of war or the armed forces" , "relating to soldiers" .)