You can find free piece sets and fonts that you can use in Arena for displaying the chess board pieces here:
Chessvariants (piece sets, other topics)
EnPassant (piece sets, other topics)
Install the Font in your Windows or WINE environment and use it in Arena under Options -> Appearance -> Chessboard -> Pieces -> Pieces from TrueType fonts and select the font.
A good example for a clock font in Arena GUI is:
digiface.ttf (Note: Download file from Webpagepublicity)
TIP by David Dahlem (USA)