Putting a silly point in is mad (6)
I believe the answer is:
insane
'is mad' is the definition.
(similar in meaning)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for insane that I've seen before include "out to lunch" , "Mentally unhinged" , "Anne is (anag) - crazy" , "Eg, gun or knife" , "Mentally ill" .)