Binder, I hesitate to say, under a pound (5)
I believe the answer is:
album
'binder' is the definition.
'i hesitate to say under a pound' is the wordplay.
'i hesitate to say' becomes 'um' (expression of hesitation).
'under' says to put letters next to each other.
'pound' becomes 'lb' ('lb' can be a synonym of 'pound').
'a'+'lb'='alb'
'um' after 'alb' is 'ALBUM'.
(Other definitions for album that I've seen before include "Music record or photo book" , "Pictures" , "Item of music released" , "(Photograph) book" , "LP, CD; blank book" .)