Is monarch having regrets about capital in Laos? (5)
I believe the answer is:
rules
'is monarch' is the definition.
I can't tell whether this definition defines the answer.
'regrets about capital in laos?' is the wordplay.
'regrets' becomes 'rues' ('rue' can be a synonym of 'regret').
'about' is an insertion indicator.
'capital in' indicates taking the first letters.
The first letter of 'laos' is 'l'.
'rues' going around 'l' is 'RULES'.
'having' is the link.
Can you help me to learn more?
(Other definitions for rules that I've seen before include "In Australia, football" , "following Queensberry?" , "is supreme, OK?" , "strips" , "Australian football" .)