Western ally discovered snap material? (2,5)

'material?' is the definition.
Both the answer and definition are adjectives.
Maybe there's an association between them I don't understand?

'western ally discovered snap' is the wordplay.
'western' becomes 'ont' (I can't justify this - if you can you should give a lot more credence to this answer).
'ally' becomes 'crony' (I've seen this in another clue).
'discovered' indicates the central letters (dis-covered - outer letters removed).
'snap' becomes 'pic' (short for picture).
The centre of 'crony' is 'o'.
'ont'+'o'+'pic'='ON TOPIC'

Can you help me to learn more?