Special collection of least well-regarded artist? (6,6)
I believe the answer is:
bottom drawer
'special collection' is the definition.
(old-fashioned term for bridal linens)
'least well-regarded artist?' is the wordplay.
'least well-regarded' becomes 'bottom'.
'artist?' becomes 'drawer' (drawer is a kind of artist).
'bottom'+'drawer'='BOTTOM DRAWER'
'of' is the link.
(Other definitions for bottom drawer that I've seen before include "Collection prior to wedding" , "Collections of singles from" , "Jeanne Lorioz?" , "Woman's store of articles kept for marriage" , "most inferior artist" .)