The Fragrance Foundation, a trade group for the perfume industry, paid former President Bill Clinton $260,000 to give a speech in January 2014 that lasted less than an hour.

In the months after the talk, the Bill, Hillary and Chelsea Clinton Foundation organized and partially funded an effort to get hundreds of farmers in Haiti to plant thousands of lime trees, a project designed to help both the impoverished farmers and the perfume and beverage industries, which had been hurt by a spike in lime prices caused by drought and crop blight.

The Clinton Foundation’s partner on the project was one of the world’s largest fragrance and flavoring suppliers, Firmenich International SA, along with the Swiss company’s U.S. charity. The Firmenich Charitable Foundation put up about $250,000 for the Haiti lime-tree project. Some of it went to a unit of the Clinton Foundation in Haiti and some to a charity recruited for the project that works with the Clinton Foundation in Haiti, records and interviews show.

Mr. Clinton’s $260,000 speaking fee wasn’t a donation to the foundation but was reported as personal income—an honorarium—on the candidate financial-disclosure form of his wife, Hillary Clinton, the Democratic nominee. The speech was one of 104 paid speeches that earned Bill and Hillary Clinton about $25 million in the 16 months before she launched her presidential campaign.

The timing of Bill Clinton’s speech income, from a perfume trade group in which a large member would later benefit from a Clinton Foundation project in Haiti, represents the kind of overlapping of private and charitable interests that has become a political liability for his wife as she runs for office. The Clinton Foundation has previously drawn attention for accepting donations from companies and foreign governments with business before the State Department when it was led by Mrs. Clinton.