My collection of items stays (6)
I believe the answer is:
corset
'stays' is the definition.
(stays can refer to a corset)
'my collection of items' is the wordplay.
'my' becomes 'cor' (both are expressions of surprise).
'collection of items' becomes 'set'.
'cor'+'set'='CORSET'
(Other definitions for corset that I've seen before include "Tight bodice" , "A woman's close-fitting support undergarment" , "Type of bodice" , "female garment!" , "Restraining undergarment" .)