That'd be the 'bond' whereby they take their passports away, force them to work 12 hours a day, six days a week for a pittance well below what they were promised (in appalling and dangerous conditions, of course), leaving them bound by debt to their employers and legally unable to appeal or demonstrate due to having pretty much no rights?
sort of.
The employers pay for their flights and accommodation (a couple of floors of a hotel one for males, one for females, for instance) and food - then deduct it from their wages.
Leaving them pretty much penniless and unable to pay for a flight out.
Other clubs never came into my thoughts once I knew Arsenal wanted to sign me.