Censor's current turnover (4)
I believe the answer is:
edit
'censor's' is the definition.
(censoring is editing out certain content)
'current turnover' is the wordplay.
'current' becomes 'tide' (sea currents).
'turnover' says the letters should be written in reverse (the letters turn over).
'tide' in reverse letter order is 'EDIT'.
(Other definitions for edit that I've seen before include "Manage a newspaper" , "Prep for press" , "Censor" , "Prepare (material) for publishing" , "What our boss does" .)