As an ingredient of gunpowder, can be a bit disconcerting (5)
I believe the answer is:
nitre
'as' is the definition.
The answer and definition can be both substances as well as being singular nouns.
Maybe you can see an association between them that I can't see?
'ingredient of gunpowder can be a bit disconcerting' is the wordplay.
'NITRE' is hidden backwards within the letters.
However, I am not sure how the hidden word is indicated.
'an' acts as a link.
Can you help me to learn more?
(Other definitions for nitre that I've seen before include "explosive producer?" , "Inert (anag) - saltpetre" , "fertiliser" , "Salt" , "what goes into bangers" .)