A doctor punching curt chap Serpent (5)
I believe the answer is:
mamba
'serpent' is the definition.
(I know that Mamba is a type of elapid)
'a doctor punching curt chap' is the wordplay.
'a doctor' becomes 'MB' (Bachelor of Medicine, Medicinae Baccalaureus).
'punching' means one lot of letters goes inside another (some letters punch a hole in others).
'curt chap' becomes 'maa' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'mb' inserted into 'maa' is 'MAMBA'.
Can you help me to learn more?
(Other definitions for mamba that I've seen before include "One's venomous" , "Snake that might kill" , "It may be deadly" , "Deadly African snake" , "Venomous snake; rhymes with dance" .)