Bird bringing a brave man to a mistaken conclusion (5)
I believe the answer is:
heron
'bird' is the definition.
(heron is a kind of bird)
'a brave man to a mistaken conclusion' is the wordplay.
'a brave man' becomes 'hero' (I've seen this before).
'conclusion' indicates one should take the final letters.
The final letter of 'mistaken' is 'n'.
'hero'+'n'='HERON'
'bringing' is the link.
(Other definitions for heron that I've seen before include "eg Egret" , "Long-legged long-necked wading bird" , "Large British wading bird" , "One bird" , "flier" .)