Language in Cardiff (5)
I believe the answer is:
welsh
'language in cardiff' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for welsh that I've seen before include "tongue" , "From Aberystwyth, perhaps" , "From Aberystwyth, for instancewelshw" , "Nationality of Dai or Ivor" , "Default on bet in Wales?" .)