Language used in school in Goa (5)
I believe the answer is:
lingo
'language' is the definition.
(informal term for language)
'in school in goa' is the wordplay.
'in' indicates a hidden word.
'LINGO' is hidden within 'school in goa'.
'used' is the link.
(Other definitions for lingo that I've seen before include "speech" , "Language, colloquially speaking." , "strange language" , "local dialect" , "Foreign language or dialect: jargon" .)