Chat about head of finance in taxi (6)
I believe the answer is:
confab
'chat' is the definition.
(I know that chat can be written as confab)
'about head of finance in taxi' is the wordplay.
'about' becomes 'on' (as in a book 'on' a certain topic).
'head of' says to take the initial letters.
'in' means one lot of letters goes inside another.
'taxi' becomes 'cab' (synonyms).
The first letter of 'finance' is 'f'.
'on'+'f'='onf'
'onf' placed inside 'cab' is 'CONFAB'.
(Other definitions for confab that I've seen before include "gossip" , "Chatter" , "natter" , "Informal discussion (colloq.)" , "Exchange" .)