Very brave (4-7)
(Other definitions for lion-hearted that I've seen before include "Brave, determined" , "Courageous" .)
'very brave' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for heroic that I've seen before include "Superhuman (efforts)" , "Like a brave man" , "Showing no fear in the face of extreme difficulty" , "Surpassing the ordinary, in courage say" , "Courageous - daring" .)