Normally one admits a grave wrong (2,7)
I believe the answer is:
on average
'normally' is the definition.
Both the definition and answer are adverbs. Maybe you can see a link between them that I don't see?
'one admits a grave wrong' is the wordplay.
'admits' indicates putting letters inside.
'wrong' is an anagram indicator.
'a'+'grave'='agrave'
'agrave' with letters rearranged gives 'averag'.
'one' going around 'averag' is 'ON AVERAGE'.
Can you help me to learn more?
(Other definitions for on average that I've seen before include "Usually" , "typically speaking" , "Generally" .)