Eco-friendly meter, we hear, for fruit (9)
I believe the answer is:
greengage
'for fruit' is the definition.
(type of plum)
'eco-friendly meter we hear' is the wordplay.
'eco-friendly' becomes 'green' (green can mean good for the environment).
'meter' becomes 'gauge' (I've seen this before).
'we hear' indicates a 'sounds like' (homophone) clue.
'gauge' is a homophone of 'gage'.
'green'+'gage'='GREENGAGE'
(Other definitions for greengage that I've seen before include "Fruit like a small plum" , "it's fruity" , "Fruit tree" , "Plum-like fruit" , "Fruit akin to plum" .)