Hairdo ... or do, as hair (5)
I believe the answer is:
style
I believe this is a double definition.
'hairdo' is the first definition.
(I know that hairdo can be written as style)
'do as hair' is the second definition.
(I've seen this in another clue)
(Other definitions for style that I've seen before include "Panache" , "Distinctive manner" , "Phraseology" , "Chic" , "Manner or look" .)