Gold fish coming into silent tomb (9)
I believe the answer is:
mausoleum
'tomb' is the definition.
(I know that mausoleum is a type of sepulcher)
'gold fish coming into silent' is the wordplay.
'gold' becomes 'Au' (Au is the chemical symbol for gold).
'fish' becomes 'sole' (sole is a kind of fish).
'coming into' indicates putting letters inside.
'silent' becomes 'mum' (synonyms).
'au'+'sole'='ausole'
'ausole' inserted within 'mum' is 'MAUSOLEUM'.
(Other definitions for mausoleum that I've seen before include "Large, stately tomb" , "Great tomb - usual memo (anag)" , "Sepulchre" , "One may lie impressively in this" , "Building with a tomb" .)