Like writers on these poplars (6)
I believe the answer is:
aspens
'these poplars' is the definition.
(aspen is a kind of poplar)
'like writers on' is the wordplay.
'like' becomes 'as'.
'writers' becomes 'pens' (I've seen this in another clue).
'on' is a charade indicator (letters next to each other).
'as'+'pens'='ASPENS'
(Other definitions for aspens that I've seen before include "The leaves of the trees flutter in the slightest breeze" , "Trees with leaves that quiver" , "Kind of poplars with shivering leaves" , "Poplar trees that shiver in the wind" , "Species of poplars with leaves that quiver" .)