Meditate (4)
I believe the answer is:
'meditate' is the definition.
(I know that meditate can be written as muse)
This is the entire clue.
(Other definitions for muse that I've seen before include "Goddess; rock group" , "Ponder or meditate" , "Contemplate -- a goddess of the liberal arts" , "Ponder, say meditatively" , "Source of artistic inspiration" .)