Splendid time of year (6)
I believe the answer is:
august
This clue is a double definition.
'splendid' is the first definition.
(thesaurus)
'time of year' is the second definition.
(month)
(Other definitions for august that I've seen before include "For Edna O'Brien, it was a 27 across month" , "Month befitting a lord" , "Month named after a Roman emperor" , "A grand month?" , "Venerable; month" .)