Beat a doctor in the final (7)
I believe the answer is:
lambast
'beat' is the definition.
(I know that lambast is a more specific form of the action beat)
'a doctor in the final' is the wordplay.
'doctor' becomes 'MB' (Bachelor of Medicine, Medicinae Baccalaureus).
'in the' indicates putting letters inside.
'final' becomes 'last' (synonyms).
'a'+'mb'='amb'
'amb' going into 'last' is 'LAMBAST'.
(Other definitions for lambast that I've seen before include "Thrash" , "Criticise severely" , "Beat severely" , "Be harsh critic of" , "Bash" .)