After time, ceremony becomes dull (5)
I believe the answer is:
trite
'dull' is the definition.
(thesaurus)
'after time ceremony' is the wordplay.
'after' says to put letters next to each other.
'time' becomes 't'.
'ceremony' becomes 'rite' (rite is a kind of ceremony).
't' next to 'rite' is 'TRITE'.
'becomes' is the link.
(Other definitions for trite that I've seen before include "Lyre string" , "Stock" , "Banal, commonplace" , "used till novelty's worn off" , "Dull, unoriginal" .)