"Secondary for improved clarity" is a persistent myth with no basis in logic or science.
Objectively, racking to secondary is actually detrimental to clarity.
After the yeast complete active fermentation, they begin falling out of solution. The cells that happen to already be near the bottom of the fermenter don't have far to go, and begin piling up at the bottom. Conversely, the cells near the top have to fall through the entire batch, so they'll take longer to precipitate out. Consequently, visually, the beer will clear from the "top down." That is, the top portion of the beer will look clear, while the remainder still appears cloudy as the cells that started out near the top slowly fall down toward the bottom.
Eventually, the top half of the beer will be clear while the bottom half still contains yeast cells making their way to the bottom. If, at this point, you were to rack the beer to another vessel, you'd be taking those cells that hadn't yet reached the bottom, and redistributing them evenly throughout the solution. Your beer wouldn't be as cloudy as it was immediately after fermentation finished (since half of the yeast cells had successfully made it to the bottom of the fermenter and would be left behind during racking), but the cells that hadn't yet made it all the way to the bottom would now be evenly mixed throughout the beer. Some of those cells would be back at the top of the solution, and would have to once again begin falling all the way through the entire batch of beer.
If that's not enough to convince you, then consider it from the other side of the argument. What is it about the presence of yeast at the bottom of the fermenter that would prevent the beer from clearing? Why would the presence of a yeast cake at the bottom of the fermenter inhibit cells in solution from precipitating out? Why would the absence of yeast at the bottom result in the beer clearing faster? There's no logical case to support the argument.
The use of secondaries is an outdated practice based on wine making and large-scale brewing, where factors like yeast autolysis are a legitimate concern, due to aging length and the higher osmotic pressure inherent in drastically larger volumes of liquid. These concerns are not valid for the short (3 weeks or less) fermentation times for beer, and the smaller volumes used at the home brewing scale.
Conclusion: The use of a secondary vessel results is no improvement in either clarity or flavour of the resulting beer. It does, however, expose the beer to an increased risk of oxidation and infection. There are legitimate cases for using a secondary vessel (only have one primary fermenter, need to re-use the yeast, need to protect the yeast from contamination from post-fermentation additions like dry hops, fruit, or wood chips, plan on aging the beer for an extended period, fermenting a large volume of beer), but for a standard 5-gallon batch of beer with no post-fermentation ingredients and no intention of extended aging, it's a pointless exercise that serves only to increase the risk of ruining the batch.
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