Notice parking by store has changed (6)
I believe the answer is:
poster
'notice' is the definition.
('poster' can be a synonym of 'notice')
'parking by store has changed' is the wordplay.
'parking' becomes 'p' (**).
'by' means one lot of letters go next to another.
'has changed' indicates anagramming the letters.
'store' anagrammed gives 'oster'.
'p'+'oster'='POSTER'
(Other definitions for poster that I've seen before include "Large sheet of paper advertising something" , "Town near Glasgow" , "Printed advert" , "Bill or placard" , "Large advert" .)