Book of maps finally cut short (5)
I believe the answer is:
atlas
'book of maps' is the definition.
(synonyms)
'finally cut short' is the wordplay.
'finally' becomes 'at last' (synonyms).
'cut short' means to remove the last letter.
'atlast' with its final letter removed is 'ATLAS'.
(Other definitions for atlas that I've seen before include "Titan who held up the sky" , "The first cervical vertebra" , "A geog. book; N. African range" , "Book of maps or charts" , "Supporter of the classics" .)