Third-rate celeb tours old monastery (8)
I believe the answer is:
cloister
'monastery' is the definition.
(I've seen this in another clue)
'third-rate celeb tours old' is the wordplay.
'third-rate' becomes 'c'.
'celeb' becomes 'lister' (I can't explain this - if you can you should believe this answer much more).
'tours' means one lot of letters goes inside another (to tour can mean to go around).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'lister' enclosing 'o' is 'loister'.
'c'+'loister'='CLOISTER'
Can you help me to learn more?
(Other definitions for cloister that I've seen before include "Place of religious seclusion, a convent say" , "Cathedral area" , "Cathedral's covered walk" , "Covered walkway round a cathedral courtyard" , "Covered walk by cathedral etc" .)