Roman poet, half-cut, gambles on hard legendary king (9)
I believe the answer is:
gilgamesh
'legendary king' is the definition.
The definition suggests a singular noun which matches the answer.
'roman poet half-cut gambles on hard' is the wordplay.
'roman poet' becomes 'virgil'.
'half cut' indicates taking half.
'gambles' becomes 'games' (I've seen this in another clue).
'on' means one lot of letters go next to another (in a down clue, letters appear on others).
'hard' becomes 'h' (abbreviation used in pencil classifications).
'virgil' cut in half is 'gil'.
'gil'+'games'+'h'='GILGAMESH'
Can you help me to learn more?
(Other definitions for gilgamesh that I've seen before include "1 28 [EPIC POEM]" , "epic character?" .)