Jack gets Rosalie no end upset! (6)
I believe the answer is:
sailor
'jack' is the definition.
(I've seen this before)
'rosalie no end upset' is the wordplay.
'no end' means to remove the last letter.
'upset' indicates an anagram.
'rosalie' with its last letter removed is 'rosali'.
'rosali' is an anagram of 'SAILOR'.
'gets' acts as a link.
(Other definitions for sailor that I've seen before include "Sinbad, for example" , "Seaman" , "Seafarer" , "Sinbad, maybe" , "10 [MARINER]" .)