Vital cure could be financially rewarding (9)
I believe the answer is:
lucrative
'financially rewarding' is the definition.
(lucrative can mean profitable or well-paid)
'vital cure could be' is the wordplay.
'could be' indicates anagramming the letters.
'vital'+'cure'='vitalcure'
'vitalcure' is an anagram of 'LUCRATIVE'.
(Other definitions for lucrative that I've seen before include "Producing a sizeable profit" , "rewarding" , "Well-paid" , "Highly profitable" , "Making money" .)