Envied being excited in tall grass (8)
I believe the answer is:
resented
'envied' is the definition.
'excited in tall grass' is the wordplay.
'excited' becomes 'sent' (send can mean to excite or stimulate).
'in' indicates putting letters inside.
'tall grass' becomes 'reed' (tall grass plant).
'sent' inserted inside 'reed' is 'RESENTED'.
'being' acts as a link.
(Other definitions for resented that I've seen before include "taken ill" , "Felt bitterness at (something)" , "Took exception" , "Considered as an insult" , "Felt bitter or indignant about" .)