American crime fighter in cape (4)
I believe the answer is:
ness
'cape' is the definition.
(I know that cape can be written as ness)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for ness that I've seen before include "Scottish loch - headland" , "Loch of monster fame" , "Scottish Lough of monster myth" , "something added for quality" , "Where you're reputed to see monster" .)