Model tug made in scale (9)
I believe the answer is:
magnitude
'scale' is the definition.
(thesaurus)
'model tug made in' is the wordplay.
'model' indicates an anagram.
'tug'+'made'+'in'='tugmadein'
'tugmadein' anagrammed gives 'MAGNITUDE'.
(Other definitions for magnitude that I've seen before include "Eating mud (anag.)" , "Relative importance" , "Largeness or size" , "Dimensions" , "(A star's) brightness" .)