Duck liver is not finished by one of The Greens (5)
I believe the answer is:
olive
'one of the greens' is the definition.
'olive' can be an answer for 'greens' (olive green is a kind of green). I am not certain of the 'one of the' bit.
'duck liver is not finished by' is the wordplay.
'duck' becomes 'o'.
'is not finished' means to remove the last letter.
'by' is a charade indicator (letters next to each other).
'liver' with its final letter taken off is 'live'.
'o'+'live'='OLIVE'
Can you help me to learn more?
(Other definitions for olive that I've seen before include "Yellowish-green colour" , "Fruit giving oil" , "Oil-yielding tree" , "Oil-yielding fruit" , "Stoned fruit" .)