A post one mishandled being stirrer (8)
I believe the answer is:
teaspoon
'being stirrer' is the definition.
(I've seen this before)
'a post one mishandled' is the wordplay.
'mishandled' is an anagram indicator.
'a'+'post'+'one'='apostone'
'apostone' with letters rearranged gives 'TEASPOON'.
(Other definitions for teaspoon that I've seen before include "5 ml container" , "Cutlery accompanying a cuppa" , "Cooking unit" , "It creates a stir" , "Kitchen utensil able to hold about one fluid dram" .)