Shoot out of Brussels? (6)
I believe the answer is:
sprout
This clue is a double definition.
'shoot' is the first definition.
('sprout' can be a synonym of 'shoot')
'brussels?' is the second definition.
(I've seen this before)
'out of' is the link.
(Other definitions for sprout that I've seen before include "Put out shoots for a brassica" , "Grow during stupor" , "Produce buds" , "Start to grow" , "Young shoot" .)