Dispassionate sort of chat in action (8)
I believe the answer is:
detached
'dispassionate' is the definition.
(synonyms)
'sort of chat in action' is the wordplay.
'sort of' indicates anagramming the letters.
'in' is an insertion indicator.
'action' becomes 'deed' (deed is a kind of action).
'chat' is an anagram of 'tach'.
'tach' put into 'deed' is 'DETACHED'.
(Other definitions for detached that I've seen before include "Separate, disconnected" , "Type of house" , "cut off" , "Clinical" , "Separated from - maybe a house" .)