Assembled a collection of old books about cult object (5)
I believe the answer is:
totem
'cult object' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'assembled a collection of old books about' is the wordplay.
'assembled' becomes 'met' ('meet' can be a synonym of 'assemble').
'a collection of old books' becomes 'ot' (I am not sure about this - if you are sure you should believe this answer much more).
'about' says the letters should be written backwards.
'met'+'ot'='metot'
'metot' in reverse letter order is 'TOTEM'.
Can you help me to learn more?
(Other definitions for totem that I've seen before include "Natural thing adopted as an emblem" , "something sacred" , "Natural object carved on poles by North American Indians" , "Sign" , "Symbolic pole" .)