Promptly abandoned in Athlone (2,3,4)
I believe the answer is:
on the nail
'promptly' is the definition.
(I've seen this before)
'abandoned in athlone' is the wordplay.
'abandoned' indicates an anagram (the original order is abandoned).
'in'+'athlone'='inathlone'
'inathlone' is an anagram of 'ON THE NAIL'.
(Other definitions for on the nail that I've seen before include "location of solution for digital protection" , "without delay" , "Promptly" , "Where a coat may be hung" , "immediately" .)