Pairs fight dust with energy (5)
I believe the answer is:
duets
'pairs' is the definition.
(duet is a kind of pair)
'fight dust with energy' is the wordplay.
I cannot quite see how this works, but
'energy' could be 'e' (physics symbol as in E=mc2) and 'e' is located in the answer.
an anagram of 'dust' is 'duts' which is located in the left over letters.
No letters remain.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for duets that I've seen before include "Works for two" , "Songs sung by two" .)