If you want grep and $c must be a reference here is one way:

#! /usr/bin/perl

$a = { aa => 'b',
       bb => 'd',
       le1 => 'sad',
       le2 => 'ss'
     } ;

my @keys = grep { ! /le/ } keys %$a ;
@$c{@keys} = @$a{@keys};

foreach (keys %$c) {
    print "key=$_ et val=$c->{$_}\n" ;
}
[download]