Models full of depression sent back for attitudes (8)
I believe the answer is:
postures
'attitudes' is the definition.
(posture is a kind of attitude)
'models full of depression sent back' is the wordplay.
'models' becomes 'poses' ('pose' can be a synonym of 'model').
'full of' is an insertion indicator.
'depression' becomes 'rut' (rut is a kind of depression).
'sent back' is a reversal indicator.
'rut' back-to-front is 'tur'.
'poses' going around 'tur' is 'POSTURES'.
'for' is the link.
(Other definitions for postures that I've seen before include "Sour pest produces poses" , "Strikes attitudes, assumes artificial positions" .)