Improved figure cutting grass (8)
I believe the answer is:
reformed
'improved' is the definition.
(reforming is a kind of improving)
'figure cutting grass' is the wordplay.
'figure' becomes 'form' (synonyms).
'cutting' is an insertion indicator (some letters cut their way into a word).
'grass' becomes 'reed' (type of grass plant).
'form' inserted within 'reed' is 'REFORMED'.
(Other definitions for reformed that I've seen before include "sort of church" , "Restored - mended one's ways" , "Changed for the better" .)