Possible Clues:

• Sharp, as wit
• Having a tip
• Indicated a direction
• What's done with tip in order to make it sharp?
• Rook, leaving Bury, coming into Hull? It's telling
• At the post office there's little interest, Edward indicated
• Sharp work recalled in poet Hughes
• Short of a note, mean to visit post office sharpish
• With a tapered tip
• Trained and incisive