Brief batting class (6)
I believe the answer is:
inform
'brief' is the definition.
(I know that brief is a more specific form of the action apprise)
'batting class' is the wordplay.
'batting' becomes 'in' (as in batting or being 'in' in cricket).
'class' becomes 'form' (synonyms).
'in'+'form'='INFORM'
(Other definitions for inform that I've seen before include "snitch?" , "Pass on knowledge" , "Certify" , "Enlighten" , "Apprise: grass!" .)