Incredibly clear, Dan's almanac (8)
I believe the answer is:
calendar
'almanac' is the definition.
(I've seen this before)
'incredibly clear dan's' is the wordplay.
'incredibly' is an anagram indicator.
'clear'+'dan'='cleardan'
'cleardan' is an anagram of 'CALENDAR'.
(Other definitions for calendar that I've seen before include "Tabular array of days" , "Chart showing months and days" , "Table of months and days" , "List of dates of land race" , "Year chart" .)