Hi,
Yes, the CPLD needs a clock.
The requirements according frequency range, and voltage levels are given in the CPLD datasheet.
There are many clock_oscillator manufacturers and even more clock_oscillator types.
Many are suitable.
The first thing you need to do:
Decide your requirements. The voltage levels are given. So basically you need to decide the frequency.
My recommendations:
* If possible use only one clock source for CPLD internal logic
* focus on those parts (frequencies) that need a very fixed clock (no "range". Like UART, USB...).
* A higher frequency clock gives more flexibility (as you can simply divide it down)
Klaus