Related Clues:

• Serious musical ability — something birds build up
• Sneer at (anag) — serious
• ''The Importance of Being ...'' (Oscar Wilde)
• 'I shall return,' say
• Monk's pledge
• 'I do,' at a wedding
• Serious attention given to bird's place
• “Now a soft kiss — / Aye, by that kiss, I ____ an endless bliss” (Keats)
• Quite sincere
• Wedding resolution
• An altar-ed "I do," e.g
• Serious article penned by Shackleton, maybe
• Very serious fellow in conversation
• Try, after husband leaves home, to be serious
• The Importance of Being __, play by Oscar Wilde