Do nothing with five ducks first in witchcraft! (6)
I believe the answer is:
voodoo
'witchcraft' is the definition.
(thesaurus)
'do nothing with five ducks first' is the wordplay.
'nothing' becomes 'o' (looks like zero - 0).
'with' is a charade indicator (letters next to each other).
'five' becomes 'v' (roman numeral).
'ducks' becomes 'oo' (I've seen this in other clues).
'first' is a charade indicator (letters next to each other).
'v' put next to 'oo' is 'voo'.
'do'+'o'='doo'
'doo' put after 'voo' is 'VOODOO'.
'in' is the link.
(Other definitions for voodoo that I've seen before include "In the air" , "Religious cult, involves witchcraft and animal deities" , "Religious cult involving witchcraft" , "West Indian witchcraft" , "Jinx" .)