Possible Clues:

• Created for a particular purpose
• 'Improvised or impromptu (2,3)'
• Latin phrase for improvisers
• Notice wine�s in short supply for this special purpose
• Having only one purpose
• A hospital brought in medic on a casual basis
• Formed just for a single purpose
• Latin notation - for a specific purpose
• Done for a particular purpose only
• For this (Latin)