Instrument or grenade exploded (4,5)
I believe the answer is:
reed organ
'instrument' is the definition.
(I know that reed organ is a type of instrument)
'or grenade exploded' is the wordplay.
'exploded' indicates an anagram.
'or'+'grenade'='orgrenade'
'orgrenade' anagrammed gives 'REED-ORGAN'.
(Other definitions for reed organ that I've seen before include "What you might hear" , "Melody Maker?" , "supports traditional services" , "musical instrument" , "Keyboard instrument, harmonium" .)