Language lesson is needed, primarily, before travel (5)
I believe the answer is:
lingo
'language' is the definition.
(lingo is a kind of language)
'lesson is needed primarily before travel' is the wordplay.
'primarily' says to take the initial letters.
'before' is a charade indicator (letters next to each other).
'travel' becomes 'go' ('go' can be a synonym of 'travel'**).
The first letters of 'lesson is needed' is 'lin'.
'lin'+'go'='LINGO'
(Other definitions for lingo that I've seen before include "Johnny Foreigner speaks one" , "Parlance" , "speech" , "Language (slang)" , "Argot" .)