Leaves theses unbound (6)
I believe the answer is:
sheets
'leaves' is the definition.
(I've seen this before)
'theses unbound' is the wordplay.
'unbound' indicates an anagram (letters unbound from their original order).
'theses' with letters rearranged gives 'SHEETS'.
(Other definitions for sheets that I've seen before include "She set them on the bed" , "Leaves" , "Bedclothes, sailing ropes and paper" , "Bed coverings for the sailor's ropes" , "Pieces of paper and bed linen" .)