Retail true rubbish? That's what you get from bookshops (10)
I believe the answer is:
literature
'what you get from bookshops' is the definition.
I can't judge whether this definition defines the answer.
'retail true rubbish?' is the wordplay.
'rubbish?' indicates an anagram (I've seen 'rubbished' mean this).
'retail'+'true'='retailtrue'
'retailtrue' anagrammed gives 'LITERATURE'.
'that's' is the link.
Can you help me to learn more?
(Other definitions for literature that I've seen before include "Books, writing, etc" , "Written works of artistic merit" , "fliers" , "Printed matter" , "What author writes" .)