Wears DayGlo necklaces on vacation (4)
I believe the answer is:
dons
'wears' is the definition.
('don' can be a synonym of 'wear')
'dayglo necklaces on vacation' is the wordplay.
'dayglo' becomes 'do' (I can't explain this - if you can you should give a lot more credence to this answer).
'on vacation' means to remove the middle letters.
'necklaces' with its centre taken out is 'ns'.
'do'+'ns'='DONS'
(Other definitions for dons that I've seen before include "Academics" , "Assumes" , "University teachers - Mafia bosses" , "Puts on -- lecturers" , "British university teachers and Spanish noblemen" .)