Possible Clues:

• Make light of what's sad, by the sound of it, at last
• Part of light inspirational poem turned to expression of grief
• If it turns sad, by the sound of it, make light of it (8)
• If it turns sad it may get light
• Conducting wire
• If in turn it sounds so sad, make light of it
• if it turns sad, one may make light of it
• Wire in light bulb
• Expression of regret after car races on the Strand
• Slender threadlike object