Possible Clues:

• Seeming real or true
• Plain and obvious
• It's obvious that Father may get up to what he is (8)
• Plain answer beginning to puzzle dad?
• Visible - plain - presumable
• It's obvious that it needs air, by the sound of it, in order to be able to succeed
• The sound of an air might make Father one like him, 31 across
• It's obvious that Father comes back to a father
• See 1
• It sounds as if air like this will make one succeed in time