Saint to encourage doctor (7)
I believe the answer is:
surgeon
'doctor' is the definition.
(I know that doctor can be written as surgeon)
'saint to encourage' is the wordplay.
'saint' becomes 's'.
'to encourage' becomes 'urgeon' (urging on is a kind of encouraging).
's'+'urgeon'='SURGEON'
(Other definitions for surgeon that I've seen before include "One operating in theatre" , "Theatre operator" , "Medical practitioner - go nurse (anag)" , "Sawbones" , "Operating medical practitioner" .)