The spymaster is on the clock every turn

Flip the timer at the start of every spymaster's turn rather than only when somebody reaches for it. The clue must be given before it runs out; if it is not, that team's turn is skipped and play passes. The printed rule sets no time limit at all — the timer is there for any player to flip at anyone taking too long, guessers included, and the rulebook even suggests flipping it on yourself. Making it automatic and one-sided is the change: every spymaster gets the same clock, and nobody has to decide when a pause has become a stall.