Last character coming in to cut grass is dim (4)
I believe the answer is:
hazy
'is dim' is the definition.
(thesaurus)
'last character coming in to cut grass' is the wordplay.
'last character' becomes 'z'.
'coming in to' means one lot of letters goes inside another.
'cut grass' becomes 'hay' (I've seen this before).
'z' put within 'hay' is 'HAZY'.
(Other definitions for hazy that I've seen before include "Blurred" , "Nebulous" , "Vague, ill-defined" , "Slightly misty, vague" , "Affected by mist - indistinct" .)