Ready with odd book about origin of computer navigational aid (10)
I believe the answer is:
breadcrumb
'navigational aid' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'ready with odd book about origin of computer' is the wordplay.
I cannot really understand how this works, but
'odd' could be 'rum' (rum can mean strange or dubious) and 'rum' is located in the answer.
'book' could be 'read' (I've seen this before) and 'read' is located in the answer.
'about' could be 'c' (circa) and 'c' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for breadcrumb that I've seen before include "Tiny piece of a loaf" , "little food" , "Bit of a loaf?" , "Loaf fragment" , "Particle of a loaf" .)