United in mess — bust possibly (6)
I believe the answer is:
statue
'bust possibly' is the definition.
(I know that bust is a type of statue)
'united in mess' is the wordplay.
'united' becomes 'U' (as in Man U, English football team).
'in' is an insertion indicator.
'mess' becomes 'state' (being in a state means being in a mess).
'u' going within 'state' is 'STATUE'.
(Other definitions for statue that I've seen before include "Firm figure" , "Noble's rank or dignity" , "Three-dimensional representation" , "Carved likeness" , "Sculptured person" .)