Money, one degree in a scale (10)
I believe the answer is:
centigrade
'a scale' is the definition.
(I've seen this before)
'money one degree' is the wordplay.
'money' becomes 'cent' (eg denomination of dollars).
'one' becomes 'i' (Roman numeral).
'degree' becomes 'grade' (synonyms).
'cent'+'i'+'grade'='CENTIGRADE'
'in' is the link.
(Other definitions for centigrade that I've seen before include "scale" , "C" , "measure of warmth" .)