I think McA pretty much got it nailed. Let me tell you what is going on.
@clk_array = %clock_sheet; will flatten the hash as a list in the form (key1, value1, key2, value2, ...). You either want just the keys, or just the values. For which, duh, keys and values could be very useful. Like:
You magically expect "@clk_array\-name" to distribute the suffix "-name" across each element. But instead the string will take each value from the array, and join them with the current value of $" which is a space by default, and then append the suffix to the whole.
To distribute the suffix over every element, you can use map: