Design of a red hat (6)
I believe the answer is:
fedora
'hat' is the definition.
(fedora is a kind of hat)
'design of a red' is the wordplay.
'design' indicates an anagram.
'of'+'a'+'red'='ofared'
'ofared' with letters rearranged gives 'FEDORA'.
(Other definitions for fedora that I've seen before include "Soft hat with band" , "Brimmed hat with creased crown" , "Headwear" , "Felt hat dented sideways" , "Type of hat" .)