Study Latin at first and make money (5)
I believe the answer is:
learn
'study' is the definition.
(synonyms)
'latin at first and make money' is the wordplay.
'at first' says to take the initial letters.
'and' means one lot of letters go next to another.
'make money' becomes 'earn' (I've seen this before).
The first letter of 'latin' is 'l'.
'l'+'earn'='LEARN'
(Other definitions for learn that I've seen before include "Gain knowledge or skills" , "Acquire information" , "Con" , "Renal (anag)" , "be taught a lesson" .)