Type of bolt secured by fan's shutters (7)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

U (U-bolt = a U-shaped metal fastener with screw threads on both ends) contained in LOVER’S (fan’s = enthusiast’s). Shutters or doors featuring horizontal slats set at an angle, to deflect rain or sun while allowing air through. Usually spelled louvres in British English; an indicator for the US spelling might have been helpful.