Solemn mood around Sabbath memorial (10)
I believe the answer is:
gravestone
'memorial' is the definition.
(I've seen this before)
'solemn mood around sabbath' is the wordplay.
'solemn' becomes 'grave' ('grave' can be a synonym of 'solemn').
'mood' becomes 'tone' (tone is a kind of mood**).
'around' indicates putting letters inside.
'sabbath' becomes 's'.
'grave'+'tone'='gravetone'
'gravetone' enclosing 's' is 'GRAVESTONE'.
(Other definitions for gravestone that I've seen before include "superior to body" , "Burial marker" , "Churchyard memorial" , "lapidary valediction" .)