Attack doctor when going in behind schedule (8)
I believe the answer is:
lambaste
'attack' is the definition.
(thesaurus)
'doctor when going in behind schedule' is the wordplay.
'doctor' becomes 'mb' (Bachelor of Medicine, Medicinae Baccalaureus).
'when' becomes 'as'.
'going in' indicates putting letters inside.
'behind schedule' becomes 'late' (I've seen this before).
'mb'+'as'='mbas'
'mbas' going inside 'late' is 'LAMBASTE'.
(Other definitions for lambaste that I've seen before include "Roast" , "Thrash - reprimand severely" , "pan" , "Am ablest to administer a beating" , "Censure severely or angrily" .)