What's found in anagram is spelling out of order (5)
I believe the answer is:
amiss
'out of order' is the definition.
('amiss' can be a synonym of 'out of order')
'what's found in anagram is spelling' is the wordplay.
'what's found in' says the answer is hidden in the clue.
'AMISS' is hidden within 'anagram is spelling'.
(Other definitions for amiss that I've seen before include "Wrorg" , "Revealing fault" , "Wrong (a girl!)" , "Out of order" , "Fallacious" .)