Container of a brown bookend (4)
I believe the answer is:
tank
'container' is the definition.
(I know that tank is a type of container)
'a brown bookend' is the wordplay.
'a brown' becomes 'tan' (tan is a kind of brown).
'bookend' becomes 'k' (I can't explain this - if you can you should believe this answer much more).
'tan'+'k'='TANK'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for tank that I've seen before include "War machine" , "Fighting vehicle" , "Fuel store" , "Army vehicle - reservoir" , "One has gun" .)