Dolefully abandons duel, organised in an act of foolishness (5)
I believe the answer is:
folly
'foolishness' is the definition.
(I know that foolishness can be written as folly)
'dolefully abandons duel organised' is the wordplay.
'abandons' suggests deleting specific letters.
'organised' is an anagram indicator.
'dolefully' with 'duel' removed is 'oflly'.
'oflly' anagrammed gives 'FOLLY'.
'in an act of' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for folly that I've seen before include "mock Gothic building" , "Fatuity" , "Silliness - stupid mistake" , "Stupidity - false building" , "'Madness, stupidity (5)'" .)