Can you see underwater? (5,6)
I believe the answer is:
depth charge
'can' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe you can see a link between them that I can't see?
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for depth charge that I've seen before include "it could cause a lot of damage" , "Anti-submarine explosive" , "Weapon against subs" , "Anti-submarine weapon" , "Anti-submarine bomb" .)