Religious groups tour Rome on vacation to reveal mysteries (7)
I believe the answer is:
secrets
'mysteries' is the definition.
(I know this)
'religious groups tour rome on vacation' is the wordplay.
I cannot quite see how this works, but
'on' could be 're' ('on' can be mean 'with reference to') and 're' is located in the answer.
'religious groups' could be 'sects' (sect is a type of religious group) and 'sects' is located in the leftover letters.
No letters remain.
This explanation may well be incorrect...
'to reveal' acts as a link.
Can you help me to learn more?
(Other definitions for secrets that I've seen before include "Concealed facts" , "Confidential data" , "Hidden facts" , "Confidential matters" , "Mysteries" .)