David, 17d is themed, an anagram ('adrift') of the first two words and one additional letter. 21d is a hidden, definition is (unusually) the Penultimate word
3 Badgering girl brought up with small notebooks (10)
HARASSMENT
A reversal (brought up, in a down clue) of SARAH (girl) + S (small) + ME (note) + NT (New Testament – books)