Language in another sentence (4)

I believe the answer is:
erse
'language' is the definition.
(historical term for Scottish Gaelic)
'in another sentence' is the wordplay.
'in' says the answer is hidden in the clue.
'ERSE' is hidden within 'another sentence'.
(Other definitions for erse that I've seen before include "Old Gaelic for the seer" , "Old Celtic language" , "Old name for Celtic languages" , "Name sometimes given to languages of the Celts in Ireland and Scotland" , "Old language spoken by strange seer" .)