McDonald's start ordering more salt, resulting in confusion (9)
I believe the answer is:
maelstrom
'confusion' is the definition.
(thesaurus)
'mcdonald's start ordering more salt' is the wordplay.
'start' indicates taking the first letters.
'ordering' indicates an anagram.
The first letter of 'mcdonald' is 'm'.
'more'+'salt'='moresalt'
'moresalt' anagrammed gives 'aelstrom'.
'm'+'aelstrom'='MAELSTROM'
'resulting in' is the link.
(Other definitions for maelstrom that I've seen before include "Powerful whirlpool" , "disorder" , "Powerful circular current of water" , "violent upheaval" , "Norwegian whirlpool" .)