Explosive container brought around by engineers (5)
I believe the answer is:
nitre
'explosive' is the definition.
(I've seen this before)
'container brought around by engineers' is the wordplay.
'container' becomes 'tin' (tin is a kind of container**).
'brought around' says the letters should be written backwards.
'by' is a charade indicator (letters next to each other).
'engineers' becomes 're' (Royal Engineers).
'tin' written backwards gives 'nit'.
'nit'+'re'='NITRE'
(Other definitions for nitre that I've seen before include "Sodium nitrate" , "A part of fertilizer" , "constituent of gunpowder" , "what goes into bangers" , "Gunpowder ingredient" .)