Linen item -- type mostly used after sleep (6)
I believe the answer is:
napkin
'linen item' is the definition.
'type mostly used after sleep' is the wordplay.
'type' becomes 'kind' (I've seen this before).
'mostly' means to remove the last letter.
'used after' says to put letters next to each other.
'sleep' becomes 'nap' (I've seen this before).
'kind' with its last letter taken away is 'kin'.
'kin' after 'nap' is 'NAPKIN'.
(Other definitions for napkin that I've seen before include "Cloth for wiping" , "Cloth square worn while eating" , "Cloth square used to protect clothing while eating" , "Diner's cloth" , "Cloth used at mealtime" .)