Possible Clues:

• Long and narrow lake I approach
• Of a line or length
• That's in line to get nothing up to your lug
• Second mate in ship of the line
• Fifty-one, almost in one dimension
• Like some thinking
• In length it is fifty-one, almost
• In line, in the inside of a king in play
• There's nothing up with your lug in that line (6)
• Nailer (anag.)