Entered Miami, excitedly, before noon (4,8)
I believe the answer is:
ante meridiem
'before noon' is the definition.
(I've seen this before)
'entered miami excitedly' is the wordplay.
'excitedly' is an anagram indicator.
'entered'+'miami'='enteredmiami'
'enteredmiami' anagrammed gives 'ANTE MERIDIEM'.
(Other definitions for ante meridiem that I've seen before include "in the morning" , "Before noon" , "A.M. in full" .)