Dam's mate (4)
I believe the answer is:
sire
'dam's mate' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sire that I've seen before include "Foal's father" , "Male parent of, say, horse" , "Male parent of an animal" , "Ancestor" , "Stallion; beget" .)