Check if the Clock app's timer is running

Try an "If" action with a "Script" condition:

...where the result is 1 when the timer is running, 0 if not (because there will be 0 menu bar items with the description "Timer").

The AppleScript is:

tell application "System Events"
	tell application process "Control Centre"
			return count of (every menu bar item of menu bar 1 whose description is "Timer")
	end tell
end tell