Doctor Who won't fight no dalek, ultimately! (4)
I believe the answer is:
cook
'doctor who won't' is the definition.
'cook' can be an answer for 'doctor' (both can mean to rig or manipulate). I am unsure of the rest of the definition.
'fight no dalek ultimately' is the wordplay.
'fight no' becomes 'coo' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'ultimately' indicates one should take the final letters.
The last letter of 'dalek' is 'k'.
'coo'+'k'='COOK'
Can you help me to learn more?
(Other definitions for cook that I've seen before include "Kitchen worker" , "Heat food" , "make a pie?" , "18th-century explorer" , "spoil" .)