Fictional Huckleberry (4)
I believe the answer is:
finn
'fictional huckleberry' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for finn that I've seen before include "EU statesman" , "Nordic" , "hero of English or American novel" , "Nationality of a citizen of Helsinki" , "eg Sibelius" .)