Suffix meaning "quality" (4)
I believe the answer is:
ness
'suffix meaning quality' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ness that I've seen before include "Loch in the Great Glen" , "Scottish Loch with legendary monster" , "Where you're reputed to see monster" , "Scottish lake with traditional monster" , "something added for quality" .)