Valiant Deputy should have the final say (7)
I believe the answer is:
doughty
'valiant' is the definition.
(I've seen this before)
'deputy should have the final say' is the wordplay.
'deputy' becomes 'dough' (I can't justify this - if you can you should give a lot more credence to this answer).
'should have' is a charade indicator (letters next to each other).
'the' becomes 't' (the is pronounced as a 't' sound in some dialects).
'final' suggests the final letters.
The final letter of 'say' is 'y'.
'dough'+'t'+'y'='DOUGHTY'
Can you help me to learn more?
(Other definitions for doughty that I've seen before include "Stout-hearted, valiant" , "Brave, resolute (arch.)" , "Fearless" .)