Storyteller's first yarn lacking originality (5)
I believe the answer is:
stale
'lacking originality' is the definition.
(stale can mean hackneyed or unimaginative)
'storyteller's first yarn' is the wordplay.
'storyteller's first' becomes 's' (1st letter of 'storyteller').
'yarn' becomes 'tale' (synonyms).
's'+'tale'='STALE'
(Other definitions for stale that I've seen before include "Musty or hackneyed" , "No longer take" , "past the sell-by date" , "Musty - out of date" , "No longer fresh" .)