Check about first of Georges to rule as monarch (5)
I believe the answer is:
reign
'rule as monarch' is the definition.
(I've seen this before)
'check about first of georges' is the wordplay.
'check' becomes 'rein' (both can mean to control or limit**).
'about' indicates putting letters inside.
'first of' indicates taking the first letters.
The first letter of 'georges' is 'g'.
'rein' placed around 'g' is 'REIGN'.
'to' acts as a link.
(Other definitions for reign that I've seen before include "Period during which someone is dominant" , "Period on the throne" , "Monarch's period" , "Predominance" , "Period of the rule of a sovereign" .)