>>747
function-lambda-expression

[1]> (defun double (x) (* x 2))
DOUBLE
[2]> #'double
#<FUNCTION DOUBLE (X) (DECLARE (SYSTEM::IN-DEFUN DOUBLE))
  (BLOCK DOUBLE (* X 2))>
[3]> (compile 'double)
DOUBLE ;
NIL ;
NIL
[4]> #'double
#<COMPILED-FUNCTION DOUBLE>
[5]> (function-lambda-expression #'double)
(LAMBDA (X) (* X 2)) ;
T ;
DOUBLE