Related Clues:

• Mark or sign with special meaning
• It stands for something else
• Emblem, representation
• A word formed from the initial letters of others
• My acorn may generate a new word from first letters
• Character or glyph representing something
• The sign of the sound of one of a pair of clashers
• Sign this with a clash, by the sound of it
• During the morning your pal gets the letters for this
• Perhaps the sign of a clashing sound
• Initially, that's a friend during the morning (7)
• Only letters from a friend during the morning
• NASA or NATO
• Word formed from the initial letters of others
• Metaphor, e.g