It is permitted to give a Play Clue to a card that can only play on the stacks after other people have played cards of the same suit. This is called a Delayed Play Clue.
We agree to treat all Play Clues as potential Delayed Play Clues.
For example, in a 3-player game:
Alice clues Bob number 2, which is a Play Clue on a 2.
Now, it is Bob's turn. If his 2 is the red 2, then he can play it right now.
However, Bob also knows that this could be a Delayed Play Clue through the yellow 1, the green 1, or the blue 1. So, Bob must wait for Cathy to play all of her 1's first before he can try to play the 2.