Mistakes published by informant overwhelmed by age (6)
I believe the answer is:
errata
'mistakes' is the definition.
(an erratum is a mistake in a printed work)
'informant overwhelmed by age' is the wordplay.
'informant' becomes 'rat' (rat is a kind of informant).
'overwhelmed by' indicates putting letters inside (inserted letters get absorbed or overwhelmed).
'age' becomes 'era' (both can mean a long time).
'rat' going into 'era' is 'ERRATA'.
'published by' is the link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for errata that I've seen before include "List of errors" , "Mistakes (Latin)" , "Mistakes in printed work" , "Misprints in a book" , "Mistakes in printed material" .)