The 24 - year - old Dundee United winger had already penned a pre-contract to join the Parkhead club in the summer - .
The two clubs agreed a fee late last night for winger to join straightaway
The 24 - year - old Dundee United winger had already penned a pre-contract to join the Parkhead club in the summer - but the two clubs agreed a fee late last night for him to join straightaway