Possible Clues:

• Try to perform forfeit without involving me
• Try having European force by castle
• Only a little relief for terrorist, shot
• Hard work requiring energy and force in proportion to time
• Achievement of force invading eastern stronghold
• Shot where force breaches European citadel
• Grading factor, in a phrase
• The act of trying hard
• 'It was a team ___'
• Make one to try hard