Possible Clues:

• Keeps undercover invention that's not right
• Does not arise from falsehood and evil
• Stages a protest, of a sort
• ___ wait (prepares to ambush)
• 'Doesn't get out of bed, which is untruthful and vicious (4,2)'
• Uses, as a hammock
• It's murder after 18 across to begin with - it explains why one stays in bed!
• Stays abed at home after first signs of severe enteric illness likely to return
• Makes a late start? One's about to get right round