Polished losing gladiator's first sword (7)
I believe the answer is:
cutlass
This clue could be a double definition.
'polished losing gladiator's first' is the first definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps you can see a link between them that I can't see?
'sword' is the second definition.
(cutlass is a kind of sword)
Can you help me to learn more?
(Other definitions for cutlass that I've seen before include "Pirate's sword" , "could hurt one, in the main" , "What Blackbeard wielded" , "Pirate sword" , "Type of sword" .)