World map ultimately detailed (5)
I believe the answer is:
atlas
'world map' is the definition.
'atlas' can be an answer for 'map' (thesaurus). I am not sure about the 'world' bit.
'ultimately detailed' is the wordplay.
'ultimately' becomes 'atlast' (ultimately means lastly).
'detailed' means to remove the last letter (the word must be end-less or 'de-tailed').
'atlast' with its last letter taken off is 'ATLAS'.
Can you help me to learn more?
(Other definitions for atlas that I've seen before include "Plans" , "Its architectural name is telamon" , "Sort of book" , "Segment of spine" , "Cartographer's work" .)