Medium, average (8)
I believe the answer is:
middling
I believe this clue is a double definition.
'medium' is the first definition.
(thesaurus)
'average' is the second definition.
(I know that average can be written as middling)
(Other definitions for middling that I've seen before include "Average, mediocre" , "So-so" , "Medium, average, fair" , "Moderate, average" .)