Crazy act involving people with time (8)
I believe the answer is:
demented
'crazy' is the definition.
(synonyms)
'act involving people with time' is the wordplay.
'act' becomes 'deed' (deed is a kind of act).
'involving' is an insertion indicator.
'people' becomes 'men' (men are people).
'with' means one lot of letters go next to another.
'time' becomes 't' (abbreviation).
'men'+'t'='ment'
'deed' going around 'ment' is 'DEMENTED'.
(Other definitions for demented that I've seen before include "Out of one's mind" , "Wild, irrational" , "Deranged, crazy" , "Driven mad, crazy" , "Nutty" .)