The best moment in the last month for Pat Phelan was walking in the Flatiron district in New York towards the latest location for his fast-growing aesthetic clinic chain on West 23rd Street in New York. Phelan had trudged those streets in a previous life as a technology entrepreneur. He knew what it was like to be in an unforgiving city fighting to win customers and raise money. Now Phelan was on his way to sign a lease to open a Sisu clinic in a building owned by the Italian family behind the luxury suit company Ermenegildo Zegna. “I almost…