Trouble with capital - painful (8)
I believe the answer is:
migraine
'trouble' is the definition.
The definition and answer can be both states of affairs as well as being singular nouns.
Maybe you can see an association between them that I don't see?
'capital painful' is the wordplay.
I cannot really understand how this works, but
'capital' could be 'ai' (resembles A1, which can mean capital or excellent) and 'ai' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
'with' acts as a link.
Can you help me to learn more?
(Other definitions for migraine that I've seen before include "may give one a sort of headache" , "Disabling headache" , "Recurrent throbbing headache" , "misery in capital area" , "attack" .)