Possible Clues:

• Women's organisation pulling father up for eavesdropping
• Listen in on half-wits upsetting father back in old Rome
• Retiring old man, one with bug
• Bug on the phone
• Surveillance technique
• A method favoured by the FBI for listening to suspect conversations?
• Spying aid
• Retired father, one with bug
• Listening device
• Bug, of a sort