Eats inside - it's an orderly quality (8)
I believe the answer is:
tidiness
'an orderly quality' is the definition.
(I've seen this before)
'eats inside it's' is the wordplay.
'eats' becomes 'dines' (dining is a kind of eating).
'inside' indicates putting letters inside.
'it's' becomes ''tis' (I've seen this before).
'dines' going into 'tis' is 'TIDINESS'.
(Other definitions for tidiness that I've seen before include "sense of order" , "good order" , "Insisted on neatness." , "Orderly quality" , "Quality of neatness and orderliness" .)