Related Clues:

• Make it to make it strong at last
• One may make it because it's in 30 across
• Make it strong at last
• Make this with strenth to show one strong at last
• By the sound of it, T is the alternative to F
• It's so trying for the defence at last
• At last a strong show of strength
• 'Strive to make it keep, by the sound of it (6)'
• Must be made with strength to be strong at last
• 'Great strength for a castle, by the sound of it (6)'
• It takes exertion because it's in a newt
• Take pains
• The work needed to replace T with F?
• It's a struggle for an amphibian to get round
• Amphibian keeps supporting endeavour