Figure turns it green (7)
I believe the answer is:
integer
'figure' is the definition.
(thesaurus)
'turns it green' is the wordplay.
'turns' indicates anagramming the letters.
'it'+'green'='itgreen'
'itgreen' with letters rearranged gives 'INTEGER'.
(Other definitions for integer that I've seen before include "Result of counting" , "rational number remains" , "A whole number, not a fraction" , "One for example" , "The whole thing" .)