Dresses down (6)
(Other definitions for preens that I've seen before include "Grooms, as a bird would" , "Grooms oneself in a vain manner" , "Trims feathers with beak" , "Titivates" , "Arranges as a bird does its feathers" .)
'dresses down' is the definition.
('chide' can be a synonym of 'dress down')
This is all the clue.
(Other definitions for chides that I've seen before include "Admonishes, reproves" , "Scolds, rebukes" , "Censures severely or angrily" , "Admonishes, rebukes" , "Admonishes, scolds" .)