Snatch forty winks on soft leather (6)
I believe the answer is:
kidnap
'snatch' is the definition.
('kidnap' can be a synonym of 'snatch')
'forty winks on soft leather' is the wordplay.
'forty winks' becomes 'nap' ('nap' can be a synonym of 'forty winks').
'on' says to put letters next to each other.
'soft leather' becomes 'kid' (I've seen this before).
'nap' after 'kid' is 'KIDNAP'.
(Other definitions for kidnap that I've seen before include "Seize by force to get ransom" , "Abduct (a person)" , "Abduct and hold for ransom" , "Small island" , "'Abduct, snatch (6)'" .)