Crazy old nurse’s point? Not so (9)
I believe the answer is:
senseless
'crazy' is the definition.
(synonyms)
'old nurse's point? not so' is the wordplay.
'old nurse' becomes 'SEN' (state-enrolled nurse).
'point?' becomes 'SE' (SE is an example).
'not so' becomes 'less' (I've seen this before).
'sen'+'se'+'less'='SENSELESS'
(Other definitions for senseless that I've seen before include "Silly" , "Mindless, pointless" , "Foolish; unconscious" , "Without reason" , "Out cold" .)