Companion has no time for book opening (9)
I believe the answer is:
chaperone
'companion' is the definition.
(I've seen this before)
'no time for book opening' is the wordplay.
I cannot really see how this works, but
'no' could be 'o' (O resembles 0) and 'o' is found in the answer.
'opening' could be 'chap' (chap is a kind of opening) and 'chap' is located in the answer.
The remaining letters 'erne' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'has' is the link.
Can you help me to learn more?
(Other definitions for chaperone that I've seen before include "Young lady's protector" , "Companion" , "child-minder?" , "Duenna" , "One overseeing" .)