An acknowledgement of minor explosion? (5,3)
I believe the answer is:
thank you
'an acknowledgement' is the definition.
(thank you is a kind of acknowledgement)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for thank you that I've seen before include "Much obliged!" , "I'm grateful" , "Polite reply (to gift)" , "Words of acknowledgement" , "Conventional expression of gratitude" .)