A T/O bearing should do it whether it's in gear or not but it could also be just on the edge of failing IE: sometimes does or doesn't make noise.
1. In neutral, hold the clutch in for a minute or two and the slowly release it. if no noise proceed to the next steps.
2. Try 1st gear again, if the noise is present, proceed to step 3
3.Try reverse and or a second gear take off
NOTE: it may not be as noticeable during gear changes as the clutch is typically released quicker and the car is moving

If it is only present when releasing the clutch in gear it could be the T/O bearing, a worn disc with the springs hitting the flywheel bolts, a loose flywheel or several other undesirable problems.

try the above and report back