Sword European unknown primarily carried before burial at sea (9)
I believe the answer is:
excalibur
'sword' is the definition.
(thesaurus)
'european unknown primarily carried before burial at sea' is the wordplay.
'european' becomes 'e' (abbreviation e.g. EU).
'unknown' becomes 'x' (algebra).
'primarily' suggests taking the first letters.
'before' is a charade indicator (letters next to each other).
'at sea' indicates anagramming the letters.
The initial letter of 'carried' is 'c'.
'burial' with letters rearranged gives 'alibur'.
'e'+'x'+'c'+'alibur'='EXCALIBUR'
(Other definitions for excalibur that I've seen before include "King Arthur's magical sword" , "Steel flourished years ago" , "Traditional weapon" , "Legendary weapon" , "King Arthur's magic sword" .)