Ace business publication with energy slowing in the end (5,3)
I believe the answer is:
after all
'in the end' is the definition.
(synonyms)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for after all that I've seen before include "I mean, when everything's said and done" , "In spite of any indications to the contrary" , "most importantly" , "in the final reckoning?" , "'In spite of what's been said and done (5,3)'" .)