Scale of US money I rate (10)
I believe the answer is:
centigrade
'scale' is the definition.
(I've seen this before)
'us money i rate' is the wordplay.
'us money' becomes 'cent' (US coin).
'rate' becomes 'grade' (synonyms).
'cent'+'i'+'grade'='CENTIGRADE'
'of' is the link.
(Other definitions for centigrade that I've seen before include "scale" , "measure of warmth" , "C" .)