A very old rogue having nothing green (7)
I believe the answer is:
avocado
'green' is the definition.
(shade of green)
'a very old rogue having nothing' is the wordplay.
'very' becomes 'v' (abbreviation).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'rogue' becomes 'cad' (I've seen this in another clue).
'having' says to put letters next to each other.
'nothing' becomes 'O' (looks like zero - 0).
'a'+'v'+'o'+'cad'+'o'='AVOCADO'
(Other definitions for avocado that I've seen before include "Dark green fruit like posh pear" , "Light green; fruit" , "Fruity type" , "Pulpy fruit" , "Evergreen" .)