Um, king in play reported before (7)
I believe the answer is:
earlier
'before' is the definition.
(synonyms)
'um king in' is the wordplay.
'um' becomes 'arlie' (I can't justify this - if you can you should give a lot more credence to this answer).
'king' becomes 'ER' (abbreviation for Edward Rex, various English kings).
'in' indicates putting letters inside.
'arlie' going within 'er' is 'EARLIER'.
'play reported' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for earlier that I've seen before include "Beforehand" , "Nearer the beginning" , "Formerly" , "Sooner in time" , "at a previous date" .)