Who's the doctor who knows how to treat it? (5)
I believe the answer is:
dalek
'knows how to treat it?' is the definition.
I don't know anything about this answer so I can't judge whether this works.
'who's the doctor' is the wordplay.
I cannot quite understand how this works, but
'doctor' could be 'd' (eg in PhD, Doctor of Philosophy) and 'd' is present in the answer.
The remaining letters 'alek' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'who' is the link.
Can you help me to learn more?
(Other definitions for dalek that I've seen before include "SF villain" , "Talking robot" , "mechanical creature" , "Robot with staccato voice" , "Hostile alien" .)