We have a right to deteriorate (4)
I believe the answer is:
wear
'deteriorate' is the definition.
(wearing is a kind of deteriorating)
'we have a right' is the wordplay.
'have' means one lot of letters go next to another.
'a right' becomes 'ar' (I've seen this in other clues**).
'we'+'ar'='WEAR'
'to' is the link.
(Other definitions for wear that I've seen before include "Dress in - impair - abrade - change course - river" , "brook" , "Become damaged by use" , "Accept" , "Tire; dress in" .)