Noddy's lack of memory brought up (5)
I believe the answer is:
moron
'noddy's' is the definition.
Both the definition and answer are singular nouns.
Perhaps you can see an association between them that I don't see?
'lack of memory brought up' is the wordplay.
'lack of' becomes 'no' (lack of money is no money).
'memory' becomes 'rom' (ROM is an example).
'brought up' says the letters should be written in reverse (in a down clue, letters go up).
'no'+'rom'='norom'
'norom' in reverse letter order is 'MORON'.
Can you help me to learn more?
(Other definitions for moron that I've seen before include "Idiot" , "Somewhat feeble-minded person" , "Blockhead" , "Wally" , "Fool" .)