Possible Clues:

• Like "fain": Abbr
• Docs that deliver
• Delivery docs, in brief
• Childbirth specialists, for short
• No longer used, in a dict
• Docs who deliver, or what this puzzle's longest entries have in common
• Like no-longer-used words, in a dict
• Dictionary cousin of arch
• Outdated, in a dict
• Out-of-date, for short