Snatch some sleep with coming back inside (6)
I believe the answer is:
kidnap
'snatch' is the definition.
('kidnap' can be a synonym of 'snatch')
'some sleep with coming back inside' is the wordplay.
'some sleep' becomes 'kip' (I've seen this before).
'with' becomes 'and' (I've seen this before**).
'coming back' shows that the letters should be reversed in order.
'inside' indicates putting letters inside.
'and' written backwards gives 'dna'.
'kip' going around 'dna' is 'KIDNAP'.
(Other definitions for kidnap that I've seen before include "Shanghai, abduct" , "Seize by force to get ransom" , "deprive it of liberty" , "Seize and hold for ransom" , "Small island" .)