Possible Clues:

• Go -- (rehearse)
• From one side to the other it's not polished at last
• Time in firm completed
• Finished with regardless of having the right
• Hospital started during Depression is finished
• In one end and out the other
• See 37-Across
• Audible cast, from beginning to end
• Channel carrying hydrogen across its length
• Having got to the end of most of the difficult part of course