Proverb, for example, popular and good (6)
I believe the answer is:
saying
'proverb' is the definition.
(thesaurus)
'for example popular and good' is the wordplay.
'for example' becomes 'say' (I've seen this before).
'popular' becomes 'in'.
'and' means one lot of letters go next to another.
'good' becomes 'g' (abbreviation).
'say'+'in'+'g'='SAYING'
(Other definitions for saying that I've seen before include "Adage, maxim" , "Articulating" , "Apophthegm" , "Epigram" , "Motto" .)