Part of shopfront, as cased by female spies? (6)
I believe the answer is:
fascia
'part of shopfront' is the definition.
'as cased by female spies?' is the wordplay.
'cased by' means one lot of letters goes inside another.
'female' becomes 'f' (abbreviation).
'spies?' becomes 'cia'.
'f'+'cia'='fcia'
'as' placed into 'fcia' is 'FASCIA'.
(Other definitions for fascia that I've seen before include "Flat surface (archit.)" , "Surface for display; dashboard" , "Detachable (mobile phone) front cover" , "Board above house or shop" , "Shopfront signboard" .)