Set of maps a sailor put up (5)
I believe the answer is:
atlas
'set of maps' is the definition.
(book of maps)
'a sailor put up' is the wordplay.
'sailor' becomes 'salt' (salt is a kind of sailor).
'put up' shows that the letters should be reversed in order.
'salt' backwards is 'tlas'.
'a'+'tlas'='ATLAS'
(Other definitions for atlas that I've seen before include "Titan who bore the sky on his shoulders" , "Segment of spine" , "world record?" , "book of world records?" , "travel book" .)