Nuts are in it for sloth (7)
I believe the answer is:
inertia
'sloth' is the definition.
(inertia can mean laziness or sloth)
'nuts are in it' is the wordplay.
'nuts' is an anagram indicator (nuts can mean crazy).
'are'+'in'+'it'='areinit'
'areinit' with letters rearranged gives 'INERTIA'.
'for' acts as a link.
(Other definitions for inertia that I've seen before include "Idleness" , "Feeling of slowness to act, as I retain" , "Disposition to do nothing" , "Tendency to do nothing or to remain unchanged" , "Disinclination to respond" .)