Possible Clues:

• Out-of-sight light
• Kind of bulb in a heat lamp
• With a frequency between the red end of the visible spectrum and microwaves
• Governing, managed to conceal source of riches — it's invisible
• Stylish brother a cardinal? I can't see it
• Drunk friend covers artist in radiation
• Spectrum part
• German woman nearly gets into debt - that doesn't normally come to light
• Find out about unusual type of radiation
• Such photography has popular female artist looking embarrassed