Chronically forgetting middle name to start off? Person’s cracking up! (7)
I believe the answer is:
amnesia
'chronically forgetting' is the definition.
'amnesia' can be an answer for 'forgetting' (I've seen this before). I'm not certain of the 'chronically' bit.
'middle name to start off? person's cracking up' is the wordplay.
'middle' indicates the central letters.
'to start off?' means to remove the first letter (I've seen 'starting off' mean this (the starting letter is removed)).
'person's' becomes 'one's' (belonging to an unspecified person).
'cracking' becomes 'ai' (resembles A1, informal term for excellent).
'up' says the letters should be written in reverse (in down clue: letters go upwards).
The middle of 'name' is 'am'.
'ai' back-to-front is 'ia'.
'ones' with its initial letter taken off is 'nes'.
'am'+'nes'+'ia'='AMNESIA'
Can you help me to learn more?
(Other definitions for amnesia that I've seen before include "Elephants won't suffer such" , "Memory-loss" , "Mental condition" , "Inability to recall" , "Clinical loss of memory" .)