UK Car Repair: Cant get out the speedometer cable Renault 19, speedometer cable, clutch cable

Question
Hello, I need to readjust the clutch cable on my Renault 19RT - 1994(engine E7J type) and, for this, I need to take out the whole facia. I'm stuck at the instruments panel because I cannot get out the speedometer cable from the gearbox. The clips of the cable retainer at the gearbox seems to be larger than the space between gearbox and chasis so, consequently, it cannot rotate in order to extract the cable. Any suggestions? Thanks.

Answer
This is hard to answer without seeing it, does the cable retainer not un-clip from the outer cable?  Otherwise can you not release it from behind the instrument?  I'm surprised that you have to go through this process to adjust the clutch, are you sure you cant do it at the bottom end?