A handcuff fetish is sexual arousal by or interest in handcuffs.
Kinkly explains Handcuff Fetish
Handcuffs are an element of BDSM culture. The handcuffs are used on the submissive as a sign of ownership and control by the Dominant. Handcuffs are also a prominent prop in many role play fantasies including law enforcement fantasies and fantasies involving restraint. They can also be used as a piece of jewelry in many cultures including fetishists, punks, and goths.