Huckleberry of fiction (4)
I believe the answer is:
finn
'huckleberry of fiction' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for finn that I've seen before include "hero in American adventures" , "Trollope's Phineas; one from Tampere" , "Someone from Turku" , "eg Sibelius" , "Sawyer's friend (from Helsinki?}" .)