Newspaper is found by us when returning sweet substance (5)
I believe the answer is:
sugar
'sweet substance' is the definition.
(I've seen this before)
'newspaper is found by us when returning' is the wordplay.
'newspaper' becomes 'rag' (informal term for a newspaper).
'is found by' is a charade indicator (letters next to each other).
'when returning' shows that the letters should be reversed in order.
'rag'+'us'='ragus'
'ragus' in reverse letter order is 'SUGAR'.
(Other definitions for sugar that I've seen before include "Term of affection" , "Sweet ingredient" , "Sweet white substance" , "Sweeten" , "Basic sweetener" .)