The clocks isnt an mot failure anyway. Mine has been through 4 mots without the dash working. Like it was said earlier, putting side lights on, with fans at full whack usually gets the rev counter working on mine, so from that you can work out what speed you are doing. Frontera speedos arent accurate anyway!! Another trick that can get it going is to hold in the odometre reset button for a while. this usually gets the speedo working, usefull for when you are passing a camera. Hope this helps.
Steve