Clue: 17 across, composer appearing in month — where reason for being late remains unknown? (4,7)
Answer: OPEN VERDICT
Explanation: Definition: w
An envelope ('appearing in') of PEN ('17 across', CAGE as an enclosure, not the composer) plus VERDI (~~Guiseppi~~ * Guiseppe Giuseppe*, that one is the composer *'2' – I read the clue as I think it ought to have appeared)* in OCT (October, 'month'). 'Late' (and 'remains'?) referring to a coroner's decision on a death. *Better late than…