How the A.B. trained in front of the staff (6,3,4)
I believe the answer is:
before the mast
'how the a b trained' is the definition.
I know nothing about this answer so I cannot tell whether this works.
'in front of the staff' is the wordplay.
'in front of' becomes 'before' (standing before means standing in front of).
'staff' becomes 'mast'.
'before'+'the'+'mast'='BEFORE THE MAST'
Can you help me to learn more?
(Other definitions for before the mast that I've seen before include "as seamen" , "(Working) as ordinary seaman" , "Serving as a seaman in a sailing ship" , "Serving as a common sailor" .)