The street one up for this office worker (5)
I believe the answer is:
steno
'this office worker' is the definition.
(I've seen this in another clue)
'the street one up' is the wordplay.
'the street' becomes 'st' (abbreviation).
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'one' reversed gives 'eno'.
'st'+'eno'='STENO'
'for' acts as a link.
(Other definitions for steno that I've seen before include "Old-fashioned secretary" , "US secretary perhaps" , "US typist" .)