Band's trunk carried by soldiers and gunners (9)
I believe the answer is:
orchestra
'band's' is the definition.
(I've seen this before)
'trunk carried by soldiers and gunners' is the wordplay.
'trunk' becomes 'chest' (I've seen this before).
'carried by' is an insertion indicator.
'soldiers' becomes 'or' (Other Rank).
'and' says to put letters next to each other.
'gunners' becomes 'ra' (Royal Artillery).
'or'+'ra'='orra'
'chest' going inside 'orra' is 'ORCHESTRA'.
(Other definitions for orchestra that I've seen before include "Assembly of musicians as in pit" , "Large body of musicians" , "Large musical group" , "LSO, for example" , "An assembly of musicians with various instruments" .)