In both #lang racket and #lang scheme, (eval form) by itself apparently runs form in a basically empty namespace. I've personally been using the following incantation for evaluating anything in the "standard" namespace:

(define (ueval x) (define ns (make-base-namespace)) (eval x ns))

Then (ueval source-code) evaluates source-code in a clean namespace with all the normal builtins, including eval.