Some conversed in Gaelic (4)
I believe the answer is:
erse
'gaelic' is the definition.
(synonyms)
'some conversed in' is the wordplay.
'some' says the answer is hidden in the clue (some parts of the word are used).
'ERSE' can be found hidden inside 'conversed in'.
(Other definitions for erse that I've seen before include "Possibly the language" , "Old language spoken by strange seer" , "Old Gaelic for the seer" , "Old name for Celtic languages" , "Kind of Gaelic for seer" .)