Refurbished loo contains very old moulding (5)
I believe the answer is:
ovolo
'moulding' is the definition.
(I know that ovolo is a type of moulding)
'refurbished loo contains very old' is the wordplay.
'refurbished' indicates anagramming the letters.
'contains' means one lot of letters goes inside another.
'very' becomes 'v' (common abbreviation).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'loo' anagrammed gives 'ool'.
'ool' placed around 'v' is 'ovol'.
'ovol'+'o'='OVOLO'
(Other definitions for ovolo that I've seen before include "decorative strip" , "Thumb" , "Convex moulding" , "Rounded architectural moulding" .)