Shark H? (10)
I believe the answer is:
hammerhead
This could be a double definition.
'shark' is the first definition.
(I know that hammerhead is a type of shark)
'h?' is the second 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?
(Other definitions for hammerhead that I've seen before include "Distinctively shaped shark" , "marine predator" , "Heavy hitter" , "Fish" , "Type of shark" .)