Madness of Dane, with time, deranged (8)
I believe the answer is:
dementia
'madness' is the definition.
(thesaurus)
'dane with time deranged' is the wordplay.
'with' means one lot of letters go next to another.
'deranged' indicates an anagram.
'dane'+'time'='danetime'
'danetime' with letters rearranged gives 'DEMENTIA'.
'of' acts as a link.
(Other definitions for dementia that I've seen before include "Detain me, having disease of old age" , "Chronic memory failure" , "Detain me in distressed state of old age" , "Disorder of mental processes caused by brain disease" , "Persistent mental disorder, perhaps due to age" .)