Feisty female to play Doctor Who, at last, enters (6)
I believe the answer is:
tomboy
'feisty female' is the definition.
'to play doctor who at last enters' is the wordplay.
I cannot really see how this works, but
'to' is within the answer.
'doctor' could be 'mb' (Bachelor of Medicine, Medicinae Baccalaureus) and 'mb' is found in the answer.
The remaining letters 'oy' is a valid word which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
(Other definitions for tomboy that I've seen before include "Girl enjoying rough outdoor activities" , "Girl said to be exhibiting boyish behaviour" , "tough girl" , "Wild, boisterous girl" , "Girl enjoying traditionally male activities" .)