Possible Clues:

• Library patron
• Author needing royalty as one temporarily in debt
• Steal up to boatman, who's in debt
• I prefer to have minimal interest in my affairs
• Blend or brew or fictional small family member?
• Any one of the small people in a series of books by Mary Norton
• Steal up to one of those pulling strokes - he's probably in your debt
• Not entirely natural athlete, one may be found in the library
• One taking out a loan
• She has loan of drill, welcoming din