A good finish on a list of tasks (6)
I believe the answer is:
agenda
'list of tasks' is the definition.
(list of tasks for a meeting)
'a good finish on a' is the wordplay.
'good' becomes 'g' (abbreviation).
'finish' becomes 'end' (synonyms).
'on' means one lot of letters go next to another.
'a'+'g'+'end'+'a'='AGENDA'
(Other definitions for agenda that I've seen before include "matters for discussion" , "List of items for discussion at a meeting" , "things to discuss" , "Table of business" , "List of things to be done or discussed" .)