Somewhere to sleep with a girl (6)
I believe the answer is:
bertha
'girl' is the definition.
'somewhere to sleep with a' is the wordplay.
'somewhere to sleep' becomes 'berth' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'with' says to put letters next to each other.
'berth'+'a'='BERTHA'
Can you help me to learn more?
(Other definitions for bertha that I've seen before include "big woman?" , "Woman's name" , "Big - - , WW1 gun" , "Breath (anag) - girl's name" , "43-ton German howitzer, Big _____" .)