Writer's inspiration (4)
I believe the answer is:
muse
'writer's inspiration' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for muse that I've seen before include "Ponder on one of nine" , "The source of an artist's inspiration" , "Source of artistic inspiration" , "Inspiring goddess" , "Inspiration for poet etc - ponder" .)