Great storyteller to run race unsteadily (9)
I believe the answer is:
raconteur
'great storyteller' is the definition.
(I know that raconteur is a type of great storyteller)
'to run race unsteadily' is the wordplay.
'unsteadily' indicates an anagram.
'to'+'run'+'race'='torunrace'
'torunrace' is an anagram of 'RACONTEUR'.
(Other definitions for raconteur that I've seen before include "entertaining his relations!" , "He tells a story well" , "Teller of anecdotes, Frenchstyle" , "One can relate well" , "A skilled storyteller, very entertaining" .)