Fight and fight again, nothing less (5)
I believe the answer is:
foray
'less' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'fight and fight again nothing' is the wordplay.
I cannot quite understand how this works, but
'nothing' could be 'o' (looks like zero - 0) and 'o' is found in the answer.
'fight' could be 'fray' (fray is a kind of fight) and 'fray' is found in the remaining letters.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for foray that I've seen before include "Depredation" , "Raid into enemy territory" , "Raid or incursion" , "Sortie" , "Brief incursion" .)