A fall, one getting a graze (7)
I believe the answer is:
cropper
'a fall' is the definition.
(thesaurus)
'one getting a graze' is the wordplay.
'one getting' means one lot of letters go next to another.
'a' becomes 'per'.
'graze' becomes 'crop' ('crop' can be a synonym of 'graze').
'per' put after 'crop' is 'CROPPER'.
(Other definitions for cropper that I've seen before include "Come a --, suffer disaster" , "Disastrous mistake or fall" , "failure" , "Heavy fall" .)