Little Billy put to sleep in Shanghai? (6)
I believe the answer is:
kidnap
'shanghai?' is the definition.
(shanghaiing is a kind of kidnaping)
'little billy put to sleep in' is the wordplay.
'little billy put' becomes 'dna' (I can't explain this - if you can you should give a lot more credence to this answer).
'to sleep' becomes 'kip' ('kip' can be a synonym of 'sleep').
'in' means one lot of letters goes inside another.
'dna' placed into 'kip' is 'KIDNAP'.
Can you help me to learn more?
(Other definitions for kidnap that I've seen before include "Small island" , "Seize, usually for ransom" , "Shanghai, abduct" , "Abduct (a person)" , "Take as hostage" .)