Beat a doctor in final (7)
I believe the answer is:
lambast
'beat' is the definition.
(lambasting is a kind of beating)
'a doctor in final' is the wordplay.
'doctor' becomes 'mb' (Bachelor of Medicine, Medicinae Baccalaureus).
'in' means one lot of letters goes inside another.
'final' becomes 'last' ('last' can be a synonym of 'final'**).
'a'+'mb'='amb'
'amb' inserted into 'last' is 'LAMBAST'.
(Other definitions for lambast that I've seen before include "Reprimand" , "Thrash" , "Harshly criticise" , "rubbish" , "Criticise severely" .)