Dealer good enough to take out his heartless brother (6)
I believe the answer is:
broker
This might be a double definition.
'dealer' is the first definition.
(I've seen this before)
'good enough to take out his heartless brother' is the second definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
Can you help me to learn more?
(Other definitions for broker that I've seen before include "Negotiate with" , "He buys and sells for others - say stocks" , "intermediary" , "Insurance or investment agent" , "One acts as an agent for others in buying and selling" .)