I'm grateful to retire in bedroom regularly finding muse (5)
I believe the answer is:
erato
'muse' is the definition.
(I know that Erato is a muse)
'i'm grateful to retire in bedroom regularly' is the wordplay.
'i'm grateful' becomes 'ta' (both can mean thank you).
'to retire' shows that the letters should be reversed in order (retire can mean to go back).
'in' is an insertion indicator.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
The alternating letters of 'bedroom' are 'ero'.
'ta' back-to-front is 'at'.
'at' going within 'ero' is 'ERATO'.
'finding' is the link.
(Other definitions for erato that I've seen before include "Lyric poetry's muse" , "One of the Muses" , "One of nine" , "verses she inspired" , "Poetic Muse ; eighteen (anag.)" .)