Jack causes me total confusion (7)
I believe the answer is:
matelot
'jack' is the definition.
(thesaurus)
'me total confusion' is the wordplay.
'confusion' indicates an anagram.
'me'+'total'='metotal'
'metotal' with letters rearranged gives 'MATELOT'.
'causes' acts as a link.
(Other definitions for matelot that I've seen before include "One at sea" , "seafarer" , "One sailor" , "Rating" , "A lot met (anag) - sailor" .)