Clue: Four characters from the Bard old hat (5)
Answer: SHAKO
Explanation: Four characters from the Bard old hat (5)
[*four characters from*] **SHAK**(espeare) + **O** (old) 
*Don't like this, as "four characters from' does not clearly indicate the first four letters, so just as easily could have been KESP or SPAE