Be eco-friendly (7)
I believe the answer is:
recycle
'be eco-friendly' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for recycle that I've seen before include "To use up left-overs" , "Convert waste to new usage" , "Use (waste) again" , "salvage for further use" , "attempt to save the world?" .)