Heading off for gender reassignment and a short conversation (8)
I believe the answer is:
exchange
'a short conversation' is the definition.
(I've seen this before)
'heading off for gender reassignment' is the wordplay.
'heading off for' means to remove the first letter.
'gender reassignment' becomes 'sexchange' (type of change).
'sexchange' with its first letter removed is 'EXCHANGE'.
'and' is the link.
(Other definitions for exchange that I've seen before include "Price of one currency in another" , "Short conversation or argument" , "Barter; switch" , "place of business" , "Altercation" .)