When we meet Brother Tod Clifton, he at first seems like a possible rival for the narrator – he's young, bright, good-looking, and has been working for the Brotherhood for three years. It becomes clear over time, however, that he's far from being the narrator's enemy; he's committed to working for the good of the Brotherhood.
The next time we see Clifton, he's selling Sambo dolls in the street. What happened? How could a bright young man go from being an active force in social progress to a street vendor who perpetuates black stereotypes? We never learn the answer to this question, although we do get some speculation from the narrator. Perhaps he realized that he was just a pawn to the Brotherhood. Perhaps he feared that the Brotherhood was just using him to make the Brotherhood look better, not to actually improve race relations in Harlem. Perhaps, tired of the hypocrisy, Clifton preferred to do something explicitly racist rather than continue being part of an organization that only pretends to help the black community.
This is all speculation, however. What we do know about Clifton is that his death triggers a series of events in the relationship between the narrator and the Brotherhood; in one sense, Clifton's death initiates the narrator's epiphanies concerning the limitations of Brotherhood ideology. Chief among these is the Brotherhood's insistence that Clifton's life does not deserve to be celebrated. Where the narrator sees the gunning down of an unarmed man – a friend and loyal colleague no less – the Brotherhood sees a racist street vendor.