Fuss about the writer starting to say goodbye (5)
I believe the answer is:
adios
'goodbye' is the definition.
(I know that goodbye can be written as adios)
'fuss about the writer starting to say' is the wordplay.
'fuss' becomes 'ado' (synonyms).
'about' indicates putting letters inside.
'the writer' becomes 'I' (the person who is writing these clues).
'starting to' indicates taking the first letters.
The first letter of 'say' is 's'.
'ado' placed around 'i' is 'adio'.
'adio'+'s'='ADIOS'
(Other definitions for adios that I've seen before include "Spanish farewell" , "Bye-bye (amigo)" , "Au revoir, amigo!" , "so long in Mexico" , "See you in Ibiza" .)