RAF signal broadcast garbled language? (9)
I believe the answer is:
franglais
'garbled language?' is the definition.
(informal blend of French and English)
'raf signal broadcast' is the wordplay.
'broadcast' indicates an anagram (letters scattered or cast around).
'raf'+'signal'='rafsignal'
'rafsignal' anagrammed gives 'FRANGLAIS'.
(Other definitions for franglais that I've seen before include "French with many English words" , ""Je suis happy", say" , "Corrupt language" , "A mix of tongues" , "informal version of language" .)