In attrition, perhaps, endlessly wary (3)
I believe the answer is:
war
'in attrition' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Maybe there's an association between them I don't understand?
'endlessly wary' is the wordplay.
'endlessly' means to remove the last letter.
'wary' with its final letter taken off is 'WAR'.
'perhaps' is the link.
Can you help me to learn more?
(Other definitions for war that I've seen before include "Hostile situation" , "Large-scale conflict" , "Fight" , "State of armed conflict" , "Sustained conflict" .)