Tabloid journalist coming in right before work (6)
'tabloid' is the definition.
(I've seen this before)
'journalist coming in right before work' is the wordplay.
'journalist' becomes 'ed' (short for editor).
'coming in' means one lot of letters goes inside another.
'right' becomes 'rt'.
'before' is a charade indicator (letters next to each other).
'work' becomes 'op' (abbreviation for opus**).
'ed' going into 'rt' is 'redt'.
(Other definitions for redtop that I've seen before include "Describes a tabloid newspaper", "Sun", "'A tabloid newspaper (3,3)'", "maybe, glowing over peak", "Tabloid newspaper, colloquially".)