I scoured the 1908 1st edition of Jack's Manual on the EUVS archive and didn't find any mention of either a Clover Leaf or Clover Club. The first listed 1910 edition on there (must be 2nd edition?) does contain a Clover Leaf, and the 1910 3rd edition does have both Leaf & Club with the recipes you have here. This would put the earliest mention (1901), earliest recipe (1901), and earliest cocktail book publication (1909) of a Clover cocktail as the Club, not the Leaf, right?
The first known recipe for Clover Leaf appears in Jacob Abraham Grohusko's 1908 'Jack's Manual', while the first reference to and recipe for a Clover Club (unearthed by David Wondrich) is in a 23 June 1901 piece in the 'New York Press'. Quotes etc above and on our Clover Leaf page.
I just looked through ALL of the 1908 edition of Jack's Manual and there is no "Clover Leaf." I'm trying to clarify exactly where you found your reference.