Very basic SignalTap question

It's a bad idea to use the signal as an acquisition clock. If you get strange readings you'll never know if it is the design faults or sampling faults due to glitches.

You can use a signal as a clock enable in Signaltap. Just sample your NEW_DATA_PS signal with the other 17, and then in the Signaltap configuration, look for the "storage qualifier" block. By default it is set to "Continuous", meaning that Signaltap will sample your signals on each clock cycle. If you set it to "Conditional" instead, then you will see a new column called "Storage Qualifier" just before the trigger column. There you can define an option that will tell Signaltap if it should sample the input or not. Set the NEW_DATA_PS storage qualifier to 1 and keep the other storage qualifiers to "don't care" and NEW_DATA_PS will act as a clock enable.