Related Clues:

• It's slippery, see — that's what we hear
• Moray-like
• Hard to capture
• Not at all settled
• Slippery and hard to catch
• Difficult to get hold of drug, see?
• Difficult to hold
• Evincing pain, text round hospital
• Like a slippery catch, hard for the blessed fellow to miss!
• Squirming in pain
• Nervously anxious
• Adjective for 51-Across
• Relating to long fish
• Eager and excited, some crossed boundary of Texas
• Hard to get hold of