Peers providing correspondence in mathematics (6)
I believe the answer is:
equals
'peers' is the definition.
('equal' can be a synonym of 'peer')
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for equals that I've seen before include "Is identical in quantity, value" , "Corresponds to" , "Peer group" , "Peers, matches" , "Persons of the same rank, for instance" .)