A trite form of dress (6)
I believe the answer is:
attire
'dress' is the definition.
(synonyms)
'a trite form' is the wordplay.
'form' indicates an anagram (another form of the letters).
'trite' with letters rearranged gives 'ttire'.
'a'+'ttire'='ATTIRE'
'of' is the link.
(Other definitions for attire that I've seen before include "Garments" , "Wear" , "Habit" , "Prepare" , "12" .)