Child's book on the Titanic supplied for magazine's subscribers (10)
I believe the answer is:
readership
'child's book' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'the titanic supplied for magazine's subscribers' is the wordplay.
I cannot quite understand how this works, but
'subscribers' could be 'readers' ('reader' can be a synonym of 'subscriber') and 'readers' is present in the answer.
The remaining letters 'hip' 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).
'on' acts as a link.
Can you help me to learn more?
(Other definitions for readership that I've seen before include "The following author has" , "academic position" , "Maybe all those enjoying Plath" , "a position at university -" , "All who see papers" .)