Possible Clues:

• See 11 Across
• Author of Das Kapital
• Communist score read out?
• Revolutionary starts to make another red xylophone
• See 48-Across
• 'Revolutions are the locomotives of history' sayer
• Who said religion 'is the opium of the people'
• Fraternal surname of comedy
• His epitaph begins 'Workers of all lands unite'
• and 17 Down: Damage by old trains et al, they spent 3 9 at 29 and 27