Encourage explosive finish (8)
I believe the answer is:
eggshell
'finish' is the definition.
(I've seen this before)
'encourage explosive' is the wordplay.
'encourage' becomes 'egg'.
'explosive' becomes 'shell' (I am not sure about this - if you are sure you should believe this answer much more).
'egg'+'shell'='EGGSHELL'
Can you help me to learn more?
(Other definitions for eggshell that I've seen before include "Fragile thing; type of paint" , "Holder of the white and yellow" , "Type of paint finish" , "protective covering?" , "that soldiers have to get through" .)