What's a recommend refactoring for this Emacs lisp snippet?

local_func.el

; I know this is super naive, but I haven't been in a Lisp for some time, and I
; haven't had to think about how best to deal with a Lisp-1.
;
; Really, all I'm trying to do here is define a local function so it's easier
; to read in the mapcar call.
;
(defun tnks--gnus-ident (idents)
    (let
        ((f (lambda (ident) (list (car ident) nil (cdr ident) nil nil nil))))
        (mapcar (lambda (i) (funcall f i)) idents)))