Carrying out naughty child, lament tone I affected (14)
I believe the answer is:
implementation
'carrying out' is the definition.
(synonyms)
'naughty child lament tone i affected' is the wordplay.
'naughty child' becomes 'imp' (informal term for a misbehaving child).
'affected' indicates anagramming the letters.
'lament'+'tone'+'i'='lamenttonei'
'lamenttonei' is an anagram of 'lementation'.
'imp'+'lementation'='IMPLEMENTATION'
(Other definitions for implementation that I've seen before include "Putting in force" , "Process of putting into effect" , "Carrying-out, fulfilment" .)