Related Clues:

• Does this make her strong enough to see you have an inclination?
• For strength you want to make a fort for it, by the sound of it
• It's hard to make such a dour mixture with us
• It was an effort for the ten of us to get so sour
• Work that's so hard may make one dour in the USA
• No walk in the park
• A guy starts a nuclear explosion that's mythically formidable
• Gruelling, strenuous
• Woman's copper - thin and mighty
• A right pair - useless and exhausting
• A right pair America finds steep
• Man takes nuclear option requiring very hard work
• Difficult to do
• Steep — hard
• The fellow managed to include ridiculous clue, fiendishly difficult