Books having indicators, ie, properly organised (12)
I believe the answer is:
dictionaries
'books' is the definition.
(dictionary is a kind of book)
'indicators ie properly organised' is the wordplay.
'properly organised' indicates anagramming the letters.
'indicators'+'ie'='indicatorsie'
'indicatorsie' with letters rearranged gives 'DICTIONARIES'.
'having' is the link.
(Other definitions for dictionaries that I've seen before include "works of reference" , "reference books" .)