In Near East it’s an explosive substance (5)
I believe the answer is:
nitre
'explosive substance' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.
'in near east it's' is the wordplay.
'in' is an insertion indicator.
'near' becomes 'nr' (abbreviation used in addresses).
'east' becomes 'e' (abbreviation).
'nr'+'e'='nre'
'nre' enclosing 'it' is 'NITRE'.
'an' acts as a link.
Can you help me to learn more?
(Other definitions for nitre that I've seen before include "safeguard against decay" , "Also known as salt-petre" , "fertiliser" , "explosive ingredient" , "explosive component" .)