Remarkable Scots centre missed by world heritage guardians (4)
I believe the answer is:
unco
'remarkable scots' is the definition.
(Scottish term for unusual)
'centre missed by world heritage guardians' is the wordplay.
'centre missed by' means to remove the middle letters.
'world heritage guardians' becomes 'UNESCO' (UN cultural organisation).
'unesco' with its middle removed is 'UNCO'.
(Other definitions for unco that I've seen before include "Very; unusual (Scots)" , "strange to 14 [GLASWEGIAN]" , "Remarkable Scottish" , "Very; odd (Scottish)" , "Unusually in Inverness" .)