Top monks like to carry books and Old Testament (6)
I believe the answer is:
abbots
'top monks' is the definition.
(I've seen this in another clue)
'like to carry books and old testament' is the wordplay.
'like' becomes 'as'.
'to carry' means one lot of letters goes inside another.
'books' becomes 'BB' (two abbreviations for book).
'and' is a charade indicator (letters next to each other).
'old testament' becomes 'ot'.
'bb'+'ot'='bbot'
'as' enclosing 'bbot' is 'ABBOTS'.
(Other definitions for abbots that I've seen before include "Leaders of groups of monks" , "Heads of orders of monks" , "Religious community heads" , "They're in charge of monks" , "Religious sorts" .)