Previously good and eager (4)
I believe the answer is:
agog
'eager' is the definition.
(thesaurus)
'previously good' is the wordplay.
'previously' becomes 'ago' (I've seen this before).
'good' becomes 'g' (abbreviation).
'ago'+'g'='AGOG'
'and' is the link.
(Other definitions for agog that I've seen before include "In state of wide-eyed expectancy" , "Eager - in suspense" , "Wide-eyed and surprised" , "Enthralled" , "Eagerly expectant" .)