Hat type (6)
(Other definitions for trilby that I've seen before include "The singer under the control of the hypnotist Svengali" , "one mesmerised" , "Soft hat with indented crown" , "Type of hat" , "A man's hat or novel by du Maurier" .)
'hat type' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for fedora that I've seen before include "Headgear" , "Soft hat with band" , "Felt hat dented sideways" , "Soft felt hat with a curled brim" , "Style of hat" .)