Possible Clues:

• Vinegar, so to speak
• Vim, vigour
• State of birth
• Whichever way you look at it, it makes one 18 down
• Animation or spiritedness
• This will make one go backwards and forwards
• Go to and fro
• Palindromic energy or vim
• Willie, ex-featherweight champion
• Go like this with sin for an enzyme