They're for putting on vegetables (6)
I believe the answer is:
greens
'vegetables' is the definition.
(green is a kind of vegetable)
'they're for putting on' is the wordplay.
I cannot quite see how this works, but
'on' could be 're' ('on' can be mean 'with reference to') and 're' is found in the answer.
The remaining letters 'gens' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for greens that I've seen before include "Leaves" , "Money" , "They're for putting on - vegetables" , "Cabbage, sprouts etc" , "Signs people should go" .)