Books of maps (7)
I believe the answer is:
atlases
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">books of maps</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for atlases that I've seen before include "Sea salt (anag.)" , "Cartographical works" , "Map books" , "Collected charts" , "navigation aids" .)