Senselessness of madness without a hint of sanity (7)
I believe the answer is:
inanity
'senselessness' is the definition.
(synonyms)
'madness without a hint of sanity' is the wordplay.
I cannot quite understand how this works, but
'a' could be 'an' and 'an' is found within the answer.
This may be the basis of clue (or it may be nonsense).
'of' acts as a link.
Can you help me to learn more?
(Other definitions for inanity that I've seen before include "Folly" , "act of stupidity" , "Foolishness" , "Being silly" , "Silliness in a tiny way" .)