Fact-filled reference
I believe the answer is:
'fact-filled reference' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for almanac that I've seen before include "Annual publication providing information like Old Moore's" , "Indicates dates" , "Annual publication containing information in a particular field" , "issue every year" , "Year book with astronomical events, tides etc" .)