### Clue: across Shamelessly go to bed with Hook — a basis for many an oath (3,4,4)
### Answer: THE GOOD BOOK 
 ### Explanation: Definition: a basis for many an oath
 **Anagram of**(Shamelessly) [GO TO BED **plus**(with) HOOK].
Defn: … viz. what one puts one's hand on while swearing to tell the truth, the whole truth and nothing but the truth.