Compete to get in Riviera (3)
I believe the answer is:
vie
'compete' is the definition.
(synonyms)
'to get in riviera' is the wordplay.
'to get' says the answer is hidden in the clue.
'VIE' can be found hidden inside 'in riviera'.
(Other definitions for vie that I've seen before include "Compete (with others)" , "I've got to contend" , "Contend, compete" , "Strive in French way?" , "Jockey" .)