Possible Clues:

• 'Let fall for the building by mistake (4,1,5)'
• Commit an indiscretion by leaving out a decent chap?
• Say something tactless and lose a real friend
• Surgery muscle strain required after doctor put foot in it?
• What the careless hodman does to offend?
• Say something tactless and let down a stout fellow
• Make a tactless remark