Number one bed (5)
I believe the answer is:
divan
'bed' is the definition.
(I've seen this before)
'number one' is the wordplay.
'number' becomes 'div' (I am not sure about this - if you are sure you should believe this answer much more).
'one' becomes 'an' (I've seen this in other clues).
'div'+'an'='DIVAN'
Can you help me to learn more?
(Other definitions for divan that I've seen before include "Couch - bed" , "Sort of bed" , "Viand (anag.)" , "resting place" , "Sideless, backless couch" .)