Letter-shaped fastener

UBOLT

Think of what secures pipes to beams with a curved metal embrace.

A "U-bolt" is a metal fastener shaped like the letter U, often used to secure pipes or other round objects to a surface. The clue plays on the literal shape of the bolt resembling the letter "U," making it a straightforward definition. Since "letter-shaped" hints at the U and "fastener" describes its function, the answer fits perfectly.