Source of troubles (8,3)
I believe the answer is:
pandoras box
'source of troubles' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for pandoras box that I've seen before include "legendary source of trouble" , "In Greek mythology, what the first woman was forbidden to open" , "Something that it's unwise to open?" , "Mythical container of all the evils of the world" , "It was disastrous, for openers" .)