Language that is somewhat hidden or secretive (5)
I believe the answer is:
norse
'language' is the definition.
(Norse is an example)
'somewhat hidden or secretive' is the wordplay.
'somewhat' says the answer is hidden in the clue.
'NORSE' can be found hidden inside 'hidden or secretive'.
'that is' is the link.
(Other definitions for norse that I've seen before include "Ancient Scandinavian language" , "Family of Germanic languages spoken in Scandinavia and Iceland" , "Old Scandinavian language" , "Native to Norway" , "Snore (anag)" .)