Cheers up in bedroom, regularly a source of inspiration (5)
I believe the answer is:
erato
'a source of inspiration' is the definition.
(I've seen this before)
'cheers up in bedroom regularly' is the wordplay.
'cheers up' becomes 'at' (I've seen this in other clues).
'in' indicates putting letters inside.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
The alternating letters of 'bedroom' are 'ero'.
'at' put within 'ero' is 'ERATO'.
(Other definitions for erato that I've seen before include "Lyric poetry's muse" , "Source of artistic inspiration" , "poetical inspiration" , "One inspiring" , "verses she inspired" .)