Possible Clues:

• Fall back, like the tide
• Retire or die back
• Withdraw and give up once more
• Go back like hairline
• Go back - like hairline?
• 21 across might do for a second sowing, by the sound of it
• Start balding
• Go backwards, hairline or tide 96)
• Decree to go backward
• Go back and do the sowing again,by the sound of it