Sinclair On Trial
Sinclair, who was released by Bradford, featured for the reserves who beat his former club 2-0 at Valley Parade thanks to goals from Scott Dobie and Robert Hughes.
Meanwhile, midfielders Kris Commons and Ross Gardner are back in training after injury lay-offs.
Neither player has been fit to feature in senior action so far this season after falling victim to respective ankle and thigh problems.
Calderwood said: 'Once we sat back and analysed how long Kris and Ross had been off, we realised they need a minimum of a week's intensive training.
'Towards the end of the week we'll have a look at Kris, but we don't want to jeopardise him by rushing him back into the game at Yeovil at the weekend - it's still in our minds, but he probably won't be involved.'
Win FREE pizza with Vital Football!
Select your team and get 50% off if they score twice.