Picked up leaf through grass (4)
I believe the answer is:
reed
'grass' is the definition.
(type of grass plant)
'picked up leaf through' is the wordplay.
'picked up' indicates a 'sounds like' (homophone) clue.
'leaf through' becomes 'read' (I've seen this in another clue).
'read' sounds like 'REED'.
(Other definitions for reed that I've seen before include "Thin strip that vibrates to produce a note" , "Marsh plant with straight hollow stem" , "Plant of marshy land" , "A blade of march grass" , "Film director" .)