(cons (car x) (clean (cdr x) :optional t)))
((cons (member &key))
(cons (car x) (clean (cdr x) :key t)))
+ ((cons (member &whole &environment))
+ ;; Skip these
+ (clean (cdr x) :optional optional :key key))
((cons cons)
(cons
(cond (key (if (consp (caar x))