Those crossed by jolly Roger? (5)
I believe the answer is:
bones
'jolly roger?' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe there's a link between them I don't understand?
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for bones that I've seen before include "Structural supports for the body" , "Elements of a skeleton" , "... skeletons, perhaps" , "Tibia, fibula etc" , "Components of skeletons" .)