Elastic band in witch's reticule (7)
I believe the answer is:
handbag
'reticule' is the definition.
(I've seen this before)
'elastic band in witch's' is the wordplay.
'elastic' indicates anagramming the letters (the anagram stretches or twists into a new form).
'in' is an insertion indicator.
'witch' becomes 'hag' (synonyms).
'band' with letters rearranged gives 'ndba'.
'ndba' going into 'hag' is 'HANDBAG'.
(Other definitions for handbag that I've seen before include "Woman's holdall?" , "Fashion accessory" , "Woman's receptacle for carrying personal items" , "Container for small personal items and money" , "Receptacle for a woman's essentials" .)