PM's counterpart entered Miami given order (4,8)
I believe the answer is:
ante meridiem
'pm's counterpart' is the definition.
(as in AM and PM on a 12-hour clock)
'entered miami given order' is the wordplay.
'given' says to put letters next to each other.
'order' indicates anagramming the letters.
'entered'+'miami'='enteredmiami'
'enteredmiami' is an anagram of 'ANTE MERIDIEM'.
(Other definitions for ante meridiem that I've seen before include "A.M. in full" , "Before noon" , "in the morning" .)