Lay to rest without royal standard (4)
I believe the answer is:
test
'standard' is the definition.
(thesaurus)
'lay to rest without royal' is the wordplay.
'without' suggests deleting specific letters.
'lay'+'to'+'rest'='laytorest'
'laytorest' with 'royal' taken out is 'TEST'.
(Other definitions for test that I've seen before include "Cricket match; exam" , "Ward off" , "Assay" , "Check" , "Trial; exam" .)