In a war of attrition, reserves of energy (3)
I believe the answer is:
fat
'reserves of energy' is the definition.
The definition and answer can be both human attributes as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'in a war of attrition' is the wordplay.
'in' indicates the answer is hidden within the clue.
'FAT' is hidden in the letters of 'war of attrition'.
Can you help me to learn more?
(Other definitions for fat that I've seen before include "Adipose tissue" , "Naturally oily substance" , "Obese, having spare tyre etc" , "Profitable" , "Excess body weight" .)