Hero down at the Den? (4)
I believe the answer is:
lion
'hero' is the definition.
(lion can mean a brave person)
'down at the den?' is the wordplay.
I cannot really see how this works, but
'at' could be 'on' (location) and 'on' is present in the answer.
The remaining letters 'li' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for lion that I've seen before include "Big cat with pride" , "Large predatory feline" , "one showing unusual courage?" , "King of sorts" , "King of the jungle" .)