Refit involving a tense exchange (12)
I believe the answer is:
conversation
'exchange' is the definition.
(thesaurus)
'refit involving a tense' is the wordplay.
'refit' becomes 'conversion'.
'involving' indicates putting letters inside.
'tense' becomes 't' (abbreviation used in many dictionaries).
'a'+'t'='at'
'conversion' placed around 'at' is 'CONVERSATION'.
(Other definitions for conversation that I've seen before include "Spoken exchange" , "Talk, chat" , "22 between people" , "discussion" , "Something to talk about?" .)