Tongue and groove's finish not as per broadcast (9)
I believe the answer is:
esperanto
'tongue' is the definition.
(I've seen this before)
'groove's finish not as per broadcast' is the wordplay.
'finish' says to take the final letters.
'broadcast' is an anagram indicator (letters scattered or cast around).
The final letter of 'groove' is 'e'.
'not'+'as'+'per'='notasper'
'notasper' is an anagram of 'speranto'.
'e'+'speranto'='ESPERANTO'
'and' is the link.
(Other definitions for esperanto that I've seen before include "Artificial international language devised in 1887" , "Language invented by Dr Zamenhof" , "composite language" , "Linguistic invention" , "largely unknown language" .)