Stern assertion from stag to his mate? (6)
I believe the answer is:
behind
'stern' is the definition.
(synonyms)
'assertion from stag to his mate?' is the wordplay.
I cannot quite see how this works, but
'from' could be 'in' (I've seen this in other clues) and 'in' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for behind that I've seen before include "Running late" , "Serving time" , "Hidden by; late" , "backing" , "Posterior, derriere" .)