Resentful longing (4)
I believe the answer is:
envy
'resentful longing' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for envy that I've seen before include "One of seven deadly sins" , "The green-eyed emotion" , "Jealous feeling" , "Resentment at another's success" , "Begrudge, covet" .)