It's blown up in home with uniform undone (9)
I believe the answer is:
euphonium
'it's blown' is the definition.
(euphonium is a kind of wind instrument)
'up in home with uniform undone' is the wordplay.
'with' is a charade indicator (letters next to each other).
'uniform' becomes 'U' (phonetic alphabet: alpha, bravo, charlie etc.).
'undone' is an anagram indicator.
'up'+'in'+'home'+'u'='upinhomeu'
'upinhomeu' with letters rearranged gives 'EUPHONIUM'.
(Other definitions for euphonium that I've seen before include "Band member" , "Wind instrument" , "Producer of notes" , "Bass-tenor tuba" , "brass piece" .)