Proportion (5)
There are a few possibilities for this:
percentage
'proportion' is the definition.
(scale is a kind of proportion)
This is all the clue.
(Other definitions for scale that I've seen before include "Climb; flake of skin" , "Climb, or series of notes in music" , "range" , "Tones rising maybe" , "Deposit in kettles, etc" .)
'proportion' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for ratio that I've seen before include "Proportion, relation" , "Measure of two relative sizes" , "Comparative measure" , "Proportion of one thing to another" , "Eg, three to one" .)
'proportion' is the definition.
(I know that percentage is a type of proportion)
This is the entire clue.
(Other definitions for percentage that I've seen before include "Proportion stated in hundredth parts" , "cut?" , "Proportion, share" , "Maybe commission" , "Proportion in each 100" .)