Trees by quiet country roads (6)
I believe the answer is:
planes
'trees' is the definition.
(I've seen this before)
'by quiet country roads' is the wordplay.
'by' says to put letters next to each other.
'quiet' becomes 'p' (music symbol for 'piano', ie soft or quiet).
'country roads' becomes 'lanes' (I've seen this before).
'p'+'lanes' is 'PLANES'.
(Other definitions for planes that I've seen before include "Aircraft and tools for smoothing wood" , "Jets maybe" , "Those flying" , "Aircraft from Naples" , "Flat surface in Naples" .)