Possible Clues:

• Get more from such seed, by the sound of it
• Do more than is warranted by
• Outclass old tennis ace utterly
• Go beyond the limit
• Former class player said to go too far
• The way to get more from what's sown, by the sound of it (6)
• Go beyond - top
• The way to get more from what you sow, by the sound of it
• Outmatch former top tennis player, say
• Go beyond the limit or norm