If upset, change the image of troublemaker (9)
I believe the answer is:
firebrand
'troublemaker' is the definition.
(I've seen this before)
'if upset change the image' is the wordplay.
'upset' shows that the letters should be reversed in order.
'change the image' becomes 'rebrand' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'if' back-to-front is 'fi'.
'fi'+'rebrand'='FIREBRAND'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for firebrand that I've seen before include "Troublemaker" , "One who stirs up trouble" , "Energetic person often fomenting trouble" , "Agitator" , "Rabble-rouser" .)