What an idiot Edward must be to have helped! (8)
I believe the answer is:
assisted
'helped' is the definition.
('assist' can be a synonym of 'help')
'what an idiot edward must be' is the wordplay.
I cannot quite see how this works, but
'an' could be 'i' (Roman numeral for one) and 'i' is present in the answer.
'idiot' could be 'ass' (I've seen this in other clues) and 'ass' is found within the answer.
'edward' could be 'ted' and 'ted' is located in the answer.
A single letter 's' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'to have' acts as a link.
Can you help me to learn more?
(Other definitions for assisted that I've seen before include "given help" , "Lent a hand" , "Aided" , "to small sibling involved in stormy dates" , "Helped" .)