Possible Clues:

• Greek letter that might make one lisp
• One slip spoilt letter
• Foreign character makes one's lip curl
• Record store never opening letter
• Greek character's quiet store in centre of Birkenhead
• Greek character's name given to old record store
• Greek character bust one's lip
• Piles on difficulty in an excerpt from Greek letters
• Electromotive force symbol
• Elasticity symbol, in economics