Brace of small fish, not old (5)
I believe the answer is:
strut
'brace' is the definition.
(I know that strut is a type of brace)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for strut that I've seen before include "Walk proudly like bantam-cock" , "Support - pompous walk" , "Stalk" , "Bar; walk stiffly" , "Take vain steps" .)