Catholic washing in loo, adult with sweaty smell (6)
I believe the answer is:
lavabo
'catholic washing' is the definition.
(I've seen this before)
'loo adult with sweaty smell' is the wordplay.
'loo' becomes 'lav' (lavatory).
'adult' becomes 'a' (abbreviation).
'with' is a charade indicator (letters next to each other).
'sweaty smell' becomes 'BO' (body odour).
'lav'+'a'+'bo'='LAVABO'
'in' acts as a link.
(Other definitions for lavabo that I've seen before include "basin" , "bathroom fitting" , "Toot" , "bowl" , "Catholic washing" .)