Illicit opportunity to dispatch Ultron at last for Marvel character (5,5)
I believe the answer is:
black widow
'dispatch ultron at last for marvel character' is the definition.
I can't tell whether this defines the answer.
'illicit opportunity' is the wordplay.
'illicit' becomes 'black' (eg the black market).
'opportunity' becomes 'widow' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'black'+'widow'='BLACK WIDOW'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for black widow that I've seen before include "Leggy creature" , "American spider, the female of which eats her mate" , "she's usually the bereaver" , "Web developer" , "Poisonous spider" .)