Rule check announced (5)
I believe the answer is:
'rule' is the definition.
(reign is a kind of rule)
'check announced' is the wordplay.
'check' becomes 'rein' (both can mean to control or limit).
'announced' indicates a 'sounds like' (homophone) clue.
'rein' sounds like 'REIGN'.
(Other definitions for reign that I've seen before include "Rule over in Niger" , "Period of the rule of a sovereign" , "Hold sway, rule" , "Period of monarch" , "Period of a monarchy" .)