Pick out loose cinders (7)
I believe the answer is:
discern
'pick out' is the definition.
('discern' can be a synonym of 'pick out')
'loose cinders' is the wordplay.
'loose' indicates anagramming the letters (letters are loosened from their original positions).
'cinders' is an anagram of 'DISCERN'.
(Other definitions for discern that I've seen before include "Make out, distinguish by eye" , "spot" , "Espy" , "Cinders (anag)" , "Perceive - distinguish" .)