The Last Seduction

The film opens in New York City, where Bridget works as a telemarketing manager and her husband Clay is training to be a doctor. He is heavily in debt to a loan shark so he arranges to sell stolen pharmaceutical cocaine to two drug dealers. The transaction becomes tense when the buyers pull a gun, but rather to Clay's surprise, they eventually pay him $700,000. Clay is left shaken, and on his return home he slaps Bridget after she insults him. She then steals the cash from him and flees their apartment while he is in the shower.
On her way to Chicago she stops in Beston, a small town near Buffalo. There she meets Mike, a local man back from a whirlwind marriage in Buffalo that he refuses to talk about, who tries to pick her up. She proceeds to use him for mere sexual gratification during her stay in town. Adept at word games and mirror writing, and with an imminent return to her hometown in mind, Bridget changes her name to Wendy Kroy and gets a job at the insurance company where, coincidentally, Mike works. Their relationship is strained by her manipulative behavior and the fact he is falling for her. When Mike tells her how to find out if a man is cheating on his wife by reading his credit reports, Bridget invents a plan based on selling murders to cheated wives. She suggests they start with Lance Collier, a cheating, wife-beating husband residing in Florida. This proves to be the last straw for Mike and he leaves her alone in his place after an argument.
Clay's thumb is broken by the loan shark for not repaying his loan. Fearing for his health and in dire financial straits, he hires a private detective, Harlan, to retrieve the money from his wife. Harlan traces her phone area code, travels to Beston and accosts Bridget at gunpoint right after her argument with Mike. She manages to murder him on the drive back to her place, and tricks the police into closing the case without further investigation by using local racial prejudice to her advantage.
She then resumes her manipulation of Mike and pretends to travel to Florida to kill Lance Collier, but instead goes to Buffalo to meet Mike's ex-wife, Trish. She shows Mike the money she stole from Clay to convince him she has taken a cut from the life insurance payout from the new widow as payment for the supposed killing. She tells him she has done it so they can live together, then tries to persuade him that he must also commit a similar murder so they will be even, and to prove that he loves her. She tries to talk Mike into killing a tax lawyer in New York City cheating old ladies out of their homes. At first he rejects the idea, but agrees after receiving a letter from his ex saying she is moving to Beston. The letter was forged by Bridget to change his mind.
Mike goes to New York and breaks into the apartment of the attorney, who turns out to be Clay. After Clay is tied up by Mike, he manages to work out what is happening when Mike mentions Bridget's alias, and convinces him of the truth by showing him a photo of himself and Bridget together. They then hatch a plot to double-cross her, but she turns the tables by killing Clay herself. She tells a stunned Mike to rape her. When he refuses, she tells him she knows the truth about Trish, who is a transsexual. This causes Mike to have rough sex with her while acting out a rape fantasy. Unbeknownst to Mike, Bridget has dialed 9-1-1 and she coaxes him into confessing to Clay's murder as part of the role play. Mike is arrested for rape and murder while she escapes with the cash and calmly destroys the only evidence that could have been used in Mike's defense.

Question: What is the reason that Clay's thumb is broken by the loan shark?
Answer: not repaying  loan; not repaying  loan