With hindsight, feud nuisance engaged in here was not warranted (5)
I believe the answer is:
undue
'not warranted' is the definition.
(I've seen this before)
'with hindsight feud nuisance engaged in here' is the wordplay.
'UNDUE' is hidden backwards within the letters.
However, I am not sure how this is indicated.
'was' acts as a link.
Can you help me to learn more?
(Other definitions for undue that I've seen before include "Excessively, unreasonably" , "too much" , "Excessive - unwarranted" , "Excessive amount" , "Not to be paid" .)