Religious people gathering shells, essentially as ornaments (6)
I believe the answer is:
jewels
'ornaments' is the definition.
(jewel is a kind of ornament)
'religious people gathering shells essentially' is the wordplay.
'religious people' becomes 'jews' (I am not sure about this - if you are sure you should believe this answer much more).
'gathering' means one lot of letters goes inside another.
'essentially' indicates the central letters.
The central letters of 'shells' are 'el'.
'jews' enclosing 'el' is 'JEWELS'.
'as' is the link.
Can you help me to learn more?
(Other definitions for jewels that I've seen before include "Finest examples" , "Adornments of gems and precious metals" , "Precious stones and minerals" , "Diamonds, rubies, sapphires etc" , "Precious stones or metals" .)