Many small kernels (6)
I believe the answer is:
scores
'many' is the definition.
(thesaurus)
'small kernels' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'kernels' becomes 'cores' ('core' can be a synonym of 'kernel').
's'+'cores'='SCORES'
(Other definitions for scores that I've seen before include "Musical compositions in written form" , "Sets of twenty" , "Scratches" , "Written forms of a musical composition" , "Written forms of musical compositions" .)