Snapshot, as it’s developed, reveals store worker (4,9)
I believe the answer is:
shop assistant
'store worker' is the definition.
(someone working in a store)
'snapshot as it's developed' is the wordplay.
'developed' is an anagram indicator.
'snapshot'+'as'+'its'='snapshotasits'
'snapshotasits' with letters rearranged gives 'SHOP-ASSISTANT'.
'reveals' is the link.
(Other definitions for shop assistant that I've seen before include "one employed in store" , "who should be helping customers?" , "Worker in retail trade" , "Salesperson" , "Give grass to aid one" .)