Purpose of action is missed first of all (3)
I believe the answer is:
aim
'purpose' is the definition.
(synonyms)
'action is missed first of all' is the wordplay.
'first of all' indicates taking the first letters.
The initial letters of 'action is missed' is 'AIM'.
'of' is the link.
(Other definitions for aim that I've seen before include "Purpose, intention" , "anticipated" , "Set sights on, target or goal" , "mission" , "Try to achieve" .)