No money for accommodation on square? Spend the night here (5)
I believe the answer is:
roost
'spend the night here' is the definition.
(where birds sleep)
'no money for accommodation on square?' is the wordplay.
'no' becomes 'O' (O resembles 0).
'money for accommodation' becomes 'ros' (I can't explain this - if you can you should believe this answer much more).
'on' indicates putting letters inside (as in clothing 'on' a person).
'square?' becomes 't' (a T-Square is a technical drawing instrument).
'o' inserted inside 'ros' is 'roos'.
'roos'+'t'='ROOST'
(Other definitions for roost that I've seen before include "Hen's resting place" , "Temporary resting-place" , "Where birds rest at night" , "Bats' settling place" , "Hen house; perch" .)