TDS is applicable only if you are crediting or paying income to the recepient and not when you are recovering money from anyone even if he receives money from you in form of any income on which TDS is applicable.
You have to deduct TDS only on the commission you credit to the brokers account. From the amount credited after TDS you can make any recovery but that recovery is not subject to TDS.
The Flow:-
Credit Brokers account with commission and recover and deposit TDS as that is his income u/s 194H.
Debit the amount recoverable from broker from whatever balance you have of his. If not sufficient, broker will have to pay to you the shortfall.