Yes, it would be clear (white light), the standard for upper fuselage I.D. (navigation) lamps at the time.
It's purpose was to indicate the position of the aircraft at night, from above, with the wing-tip nav lamps (red port, and green or blue starboard) showing the direction of travel, and was / is based on the same arrangement for ships, where the 'white' light would be on the masthead.
Today, on current aircraft, this has mainly been replaced by a bright red, strobe 'anti-collision' beacon on the upper fuselage and or fin, and some currently airworthy 'warbirds' might have a red light replacing the 'white', depending on local authority regulations.