It's bound to contain maps (5)
I believe the answer is:
atlas
'maps' is the definition.
(printed collection of maps)
'it's bound to contain' is the wordplay.
'it' becomes ''t' (abbreviation. e.g. in 'tis).
'bound' becomes 'alas' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'to contain' means one lot of letters goes inside another.
't' inserted within 'alas' is 'ATLAS'.
Can you help me to learn more?
(Other definitions for atlas that I've seen before include "Legendary weightlifter" , "Titan who supported the heavens" , "Size of paper once" , "Its architectural name is telamon" , "African mountain range" .)