Possible Clues:

• A hopeless undertaking or effort
• Hopeless effort or undertaking, beyond rescue
• Cries of distress from the crow who could not find its way home?
• Oral communication problem for crow with dead duck?
• 'The sound of a crow that can't get home is hopeless (4,5)'
• Couldn't find reason for failed campaign
• Situation that's not worth trying to fix
• You can't save this cad poked by holy person roughly
• Clueless with 23 down? Presumably, St Jude wouldn't find this challenging!
• Cook cassoulet? It's not worth the effort