Presence of poet set girl off (11)
I believe the answer is:
poltergeist
'presence' is the definition.
(I have seen 'disruptive presence' mean 'poltergeist' so perhaps 'presence' could also mean 'poltergeist')
'poet set girl off' is the wordplay.
'off' indicates anagramming the letters.
'poet'+'set'+'girl'='poetsetgirl'
'poetsetgirl' is an anagram of 'POLTERGEIST'.
'of' is the link.
(Other definitions for poltergeist that I've seen before include "Mischievous ghost" , "Disturbing ghost" , "Mischievous spirit" , "Noisy spook" , "disruptive presence" .)