She inspires weary author occasionally (5)
I believe the answer is:
erato
'she inspires' is the definition.
(one of the Greek muses)
'weary author occasionally' is the wordplay.
'occasionally' indicates alternate letters.
'weary'+'author'='wearyauthor'
The alternating letters of 'wearyauthor' are 'ERATO'.
(Other definitions for erato that I've seen before include "Poet's inspiration" , "verses she inspired" , "Who may have inspired poetry" , "One of the Muses" , "Clio's sister" .)