Dad forgot damn, demonic aide-memoire (8)
I believe the answer is:
mnemonic
'aide-memoire' is the definition.
(I've seen this before)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for mnemonic that I've seen before include "It reminds us" , "It aids recall" , "Something by which to remember" , "Trigger for the memory" , "Verse or other aid to help one remember facts" .)