Related Clues:

• Master with hidden pawn to bring into play
• Authority with no power to wield
• Make an effort to see specialist, when lacking power
• Wield cross held in upturned palm perhaps
• Strain river, right?
• Proficient, but with no power to wield
• Apply, as elbow grease
• Make good use of maestro when piano's unavailable
• Use final bits of underwater equipment beneath river
• Give one's all with
• Apply, as energy
• Use, as force
• Exercise influence to remove bolt from letter box
• Apply, as effort
• Use, as great effort