Broker might briefly note the French snake, perhaps? (7)
I believe the answer is:
reptile
'snake perhaps?' is the definition.
(I know that snake is a type of diapsid)
'broker might briefly note the french' is the wordplay.
'broker might briefly' becomes 'rep' (I can't explain this - if you can you should give a lot more credence to this answer).
'note' becomes 'ti' (musical note, as in do re mi so fa la ti do).
'the french' becomes 'le' ('the' in French).
'rep'+'ti'+'le'='REPTILE'
Can you help me to learn more?
(Other definitions for reptile that I've seen before include "loathsome type" , "Cold-blooded animal like lizard or snake" , "Unpleasant character" , "Despicable sort" , "Cold-blooded vertebrate" .)