Purpose at home? Cutting grass (5)
I believe the answer is:
point
'purpose' is the definition.
(I've seen this before)
'home? cutting grass' is the wordplay.
'home?' becomes 'in' ('he's home' can mean 'he's in').
'cutting' means one lot of letters goes inside another (some letters cut their way into a word).
'grass' becomes 'pot' (cannabis).
'in' put inside 'pot' is 'POINT'.
'at' is the link.
(Other definitions for point that I've seen before include "rocks?" , "Dot -- full stop" , "Repair brickwork" , "Bearing - precise moment" , "meaning" .)