Naval hero known to be a circus performer (3,4)
I believe the answer is:
sea lion
'circus performer' is the definition.
(I've seen this in another clue)
'naval hero known to be a' is the wordplay.
I cannot quite understand how this works, but
'hero' could be 'lion' (lion can mean a brave person) and 'lion' is located in the answer.
'a' is within the answer.
The remaining letters 'se' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for sea lion that I've seen before include "Aquatic mammal - code name for planned German invasion of England, 1940" , "Acrobatic aquatic mammal" , "Marine animal, used as a circus performer" , "Large marine mammal" , "Large-eared mammal of Pacific Ocean, like Leo" .)