Agree to study remedy briefly (6)
I believe the answer is:
concur
'agree' is the definition.
(synonyms)
'study remedy briefly' is the wordplay.
'study' becomes 'con' (conning is a kind of studying).
'remedy' becomes 'cure' (synonyms).
'briefly' means to remove the last letter.
'cure' with its final letter taken off is 'cur'.
'con'+'cur'='CONCUR'
'to' is the link.
(Other definitions for concur that I've seen before include "meet" , "See eye to eye" , "Express agreement" , "'Agree, coincide (6)'" , "run together" .)