Single man emptied grave (6)
I believe the answer is:
solemn
'grave' is the definition.
(I know that grave can be written as solemn)
'single man emptied' is the wordplay.
'single' becomes 'sole' (synonyms).
'emptied' suggests removing the centre.
'man' with its centre removed is 'mn'.
'sole'+'mn'='SOLEMN'
(Other definitions for solemn that I've seen before include "Serious; deeply sincere" , "Formal, ceremonial" , "Grave and serious about melons" , "Marked by pomp or ceremony" , "pious" .)