capacitor in series with lamp
No, the bulb should not flicker.
The calculations are as follows:

v bulb  120,
P bulb  6,
V supply    220,
f supply    50,

I bulb  0.05,
R bulb  2400,
Z tot   4400

Z tot squared   19360000,
R bulb squared  5760000,
Z required Squared  13600000,
Z required  3687.817783,

C reqd  8.6314E-07,
L reqd  11.7386985,

To use an inductor would require 12H, so too large for practical purposes.
! capacitor 820nF or 1uF would be OK. Use a plastic capacitor of the full voltage rating of the supply. Some plastic capacitors degrade over time and will result in dimming of the bulb. A good plan would be to use a Y rated capacitor as these are designed to fail open circuit prevent the bulb from exploding if the cap fails. They also are good quality as they are made to meet high standards for safety. You could use a resistor (2k) but it would dissipate 5W.