An inspiring figure to guide the monarch (6)
I believe the answer is:
leader
'an inspiring figure' is the definition.
'guide the monarch' is the wordplay.
'guide' becomes 'lead' ('lead' can be a synonym of 'guide').
'the monarch' becomes 'er' (abbreviation for Elizabeth Regina).
'lead'+'er'='LEADER'
'to' is the link.
(Other definitions for leader that I've seen before include "source of inspiration" , "Head of an orchestra" , "Principal first violinist" , "One is ahead and shows the way" , "Person in charge" .)