Races broadcast interrupted by races broadcast (7)
I believe the answer is:
scatter
'broadcast' is the definition.
(broadcast can mean to scatter seeds)
'races broadcast interrupted by races' is the wordplay.
'broadcast' indicates an anagram (letters scattered or cast around).
'interrupted by' means one lot of letters goes inside another.
'races' becomes 'tt' (Isle of Man Tourist Trophy races).
'races' with letters rearranged gives 'scaer'.
'scaer' placed around 'tt' is 'SCATTER'.
(Other definitions for scatter that I've seen before include "Throw in various directions" , "Distribute loosely" , "Sprinkle" , "Separate and move off in different directions" , "Disperse, thrown around" .)