"Steven was a target of ours and it's been a hard deal to do, but we got there in the end," Burnley manager Sean Dyche told the club's website (www.burnleyfootballclub.com).
"He's a good player with a depth of experience at international level and also Champions League.
"Steven is new to the Premier League but has a real thirst and desire to be successful in this campaign."
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The defensive midfielder became Anderlecht's record signing when he joined in 2014 after three seasons with Porto where he won two Portuguese crowns.
Defour previously played for Genk and Standard Liege, the club where he twice won the Belgian title, and has won 46 caps for the Belgian national side.
Burnley were defeated 1-0 by Swansea City in their Premier League opener on Saturday, and host Liverpool at Turf Moor this weekend.
(Reporting by Ed Dove; editing by Sudipto Ganguly)
