Make out that cinders are sifted (7)
I believe the answer is:
discern
'make out' is the definition.
(synonyms)
'cinders are sifted' is the wordplay.
'are sifted' is an anagram indicator.
'cinders' is an anagram of 'DISCERN'.
'that' is the link.
(Other definitions for discern that I've seen before include "Recognise, find out" , "Detect" , "Espy" , "Make out, distinguish by eye" , "spot" .)