Article 20The relevant part of the Article basically states that Training Compensation shall be paid to a player's training club each time a professional is transferred until the end of the season of his 23rd birthday. Then it directs us to Annexe 4 of the Regulations, which states that a player's training and education takes place between the ages of 12 and 23, and that training compensation shall be payable, as a general rule, for training up to the age of 21. I'm guessing that only if the player made remarkable massive steps forward at a club between 21 and 23 will compensation be payable to his club(s) in that period, hence why Millwall are unable to claim anything. The calculation of the amount payable is based on the years between the age of 12 and the age when the player actually completes his training. One of the main requirements for this rule is that compensation is due when a professional is transferred between clubs of 2 different associations before the end of his 23rd birthday, so it is outwith the FA's control.
So, in summary, Clyde are due money from Millwall, and that they'll be negotiating amounts. For Madaschi's loan spell in some wee club they got 30k, so i'd think Clyde would get a bit more since it's based on the time spent training a player up to standard.