Taking part in the procession is simply heaven! (8)
I believe the answer is:
paradise
'heaven' is the definition.
(I know that heaven can be written as paradise)
'taking part in the procession is' is the wordplay.
'taking part in' indicates putting letters inside.
'the procession' becomes 'parade' (parade is a kind of procession).
'parade' going around 'is' is 'PARADISE'.
'simply' is the link.
I am not very happy about this link. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for paradise that I've seen before include "Garden of Eden" , "Utopia" , "Scene of bliss" , "heavenly destination" , "Eden; ideal place" .)