Possible Clues:

• Something very small that's jumped upon, we hear
• Drachma division
• Greek currency soared, we hear, subject to ...
• Boarded with enthusiasm, aircraft's heading out for old bit of Athens
• Observe learner keeping quiet — backward type interacting weakly
• Particle quietly splitting gave the game away
• Accommodation restricts parking around new and old Greek capital
• Lop ten off the elementary particle
• 1970s TV series set at 165 Eaton Place
• One hundredth of a drachma, once