... set off, all upset to see girl (6)
I believe the answer is:
stella
'girl' is the definition.
'set off all upset' is the wordplay.
'off' indicates anagramming the letters.
'upset' says the letters should be written backwards.
'all' back-to-front is 'lla'.
'set' is an anagram of 'ste'.
'ste'+'lla'='STELLA'
'to see' acts as a link.
(Other definitions for stella that I've seen before include "Paul McCartney's daughter" , "Girl's name meaning star" , "lady?" , "woman" , "girl!" .)