Language, in another sense (4)
I believe the answer is:
erse
'language' is the definition.
(historical term for Scottish Gaelic)
'in another sense' is the wordplay.
'in' says the answer is hidden in the clue.
'ERSE' can be found hidden inside 'another sense'.
(Other definitions for erse that I've seen before include "Name sometimes given to languages of the Celts in Ireland and Scotland" , "Possibly the language" , "Celtic tongue" , "Old Celtic language" , "Kind of Gaelic for seer" .)