Distraught leaders of trade union split trophy (3,2)
I believe the answer is:
cut up
'distraught' is the definition.
('cut up' can mean very distressed)
'leaders of trade union split trophy' is the wordplay.
'leaders of' says to take the initial letters.
'split' indicates putting letters inside.
'trophy' becomes 'cup' (cup is a kind of trophy).
The initial letters of 'trade union' is 'tu'.
'tu' inserted inside 'cup' is 'CUT-UP'.
(Other definitions for cut up that I've seen before include "so treated by another driver?" , "Extremely upset" , "Miserable" , "Dissect" , "collage" .)