Recollected happiest commemorations (8)
I believe the answer is:
epitaphs
'commemorations' is the definition.
(epitaph is a kind of commemoration)
'recollected happiest' is the wordplay.
'recollected' indicates anagramming the letters (letters recollected and rearranged).
'happiest' is an anagram of 'EPITAPHS'.
(Other definitions for epitaphs that I've seen before include "words in grave situations" , "They're written in memory of people who have died" , "Happiest sort of inscriptions on tombs" , "Famous last words" , "Gravestone inscriptions" .)