What's set to explode? (9)
I believe the answer is:
gelignite
'what's set to explode?' is the definition.
I can't tell whether this definition defines the answer.
'set to explode?' is the wordplay.
'set' becomes 'gel' (both can mean to harden).
'to explode?' becomes 'ignite' (I can't explain this - if you can you should give a lot more credence to this answer).
'gel'+'ignite'='GELIGNITE'
Can you help me to learn more?
(Other definitions for gelignite that I've seen before include "High explosive" , "Tieing leg up in explosive" , "(E.g. quarry) explosive" , "Explosive used in mining" , "factor in altering mine?" .)