One often hailed monarch once as icon of the Highlands (5)
I believe the answer is:
caber
'icon of the highlands' is the definition.
(as in the caber toss at the Highland Games)
'one often hailed monarch once' is the wordplay.
'one often hailed' becomes 'cab' (you can hail a cab).
'monarch once' becomes 'ER' (Elizabeth Regina, ie Queen Elizabeth).
'cab'+'er'='CABER'
'as' is the link.
(Other definitions for caber that I've seen before include "requirement for Highland fling?" , "Tree trunk tossed in sport" , "Trunk sent up" , "One taking a toss" , "Brace (anag) - pole" .)