Cable ran broadcast showing hanger-on (8)
I believe the answer is:
barnacle
'hanger-on' is the definition.
(thesaurus)
'cable ran broadcast' is the wordplay.
'broadcast' indicates anagramming the letters.
'cable'+'ran'='cableran'
'cableran' anagrammed gives 'BARNACLE'.
'showing' acts as a link.
(Other definitions for barnacle that I've seen before include "Shellfish that sticks to things" , "Hull resident (one who clings on)?" , "On the coast it's hard to remove" , "kind of goose" , "Crusty lodger" .)