Supreme Supreme (4)
I believe the answer is:
'supreme supreme' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ross that I've seen before include "-- And Cromarty, former county of Scotland" , "Diana --, Motown singer" , "Wye town; Antarctic sea" , "Diana - (Supremes)" , "- and Cromarty, former Scottish county" .)