Something unusual, perhaps collectable (6)
I believe the answer is:
rarity
This clue is a double definition.
'something unusual' is the first definition.
(I've seen this before)
'perhaps collectable' is the second definition.
(I know that collectable is a type of rarity)
(Other definitions for rarity that I've seen before include "Infrequent occurrence" , "something out of the ordinary" , "Something valued for its scarceness" , "Collector's item" , "Something very scarce, probably valuable" .)