Wherefore, reportedly, sci-fi writer briefly identifies winged dragon (6)
I believe the answer is:
wyvern
'winged dragon' is the definition.
'wherefore reportedly sci-fi writer briefly' is the wordplay.
'wherefore reportedly' becomes 'wy' (I can't justify this - if you can you should believe this answer much more).
'sci-fi writer' becomes 'verne' (Jules Verne).
'briefly' means to remove the last letter.
'verne' with its final letter removed is 'vern'.
'wy'+'vern'='WYVERN'
'identifies' acts as a link.
(Other definitions for wyvern that I've seen before include "Heraldic winged monster" , "Fabulous creature" , "Dragon with wings in medieval heraldry" , "Heraldic device" , "Heraldic form of dragon" .)