Mythical wife evincing regret about early end to game (8)
I believe the answer is:
eurydice
'mythical wife' is the definition.
'Eurydice' can be an answer for 'wife' (wife of Orpheus in Greek mythology). I also know that 'mythical' relates to this answer.
'evincing regret about early end to game' is the wordplay.
'evincing regret' becomes 'rue'.
'about' says the letters should be written in reverse.
'end' says to take the final letters.
'to game' becomes 'dice' (**).
The final letter of 'early' is 'y'.
'rue' back-to-front is 'eur'.
'eur'+'y'+'dice'='EURYDICE'
(Other definitions for eurydice that I've seen before include "In Greek mythology, the wife of Orpheus" , "Badly-looked-after wife" , "Wife of Orpheus, who sought her in the underworld" .)