Flabbergast, being contrary and deranged (4)
I believe the answer is:
nuts
'deranged' is the definition.
(thesaurus)
'flabbergast being contrary' is the wordplay.
'flabbergast' becomes 'stun' (I've seen this in another clue).
'being contrary' shows that the letters should be reversed in order.
'stun' backwards is 'NUTS'.
'and' is the link.
(Other definitions for nuts that I've seen before include "Crackers - or what crackers are required for?" , "'Here we go gathering . . . . In May'" , "out to lunch" , "One eats these" , "Hard-shelled fruits or seeds" .)