Sound judgment soon edges away (4,5)
I believe the answer is:
good sense
'sound judgment' is the definition.
(I've seen this before)
'soon edges away' is the wordplay.
'away' indicates an anagram (letters move away from their original places).
'soon'+'edges'='soonedges'
'soonedges' is an anagram of 'GOOD SENSE'.
(Other definitions for good sense that I've seen before include "sound practical judgement" , "Sound judgment" , "Sound thinking" .)