It's an advantage to trim the lawn (4)
I believe the answer is:
edge
This might be a double definition.
'it's an advantage' is the first definition.
(having the edge is having an advantage)
'trim the lawn' is the second definition.
'edge' can be an answer for 'trim' (I've seen this in another clue). I'm not sure about the 'the lawn' bit.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for edge that I've seen before include "incisiveness" , "Bind" , "Excitement; boundary" , "Creep" , "Move slowly" .)