Employed by London-based newspaper now and again (2,5)
I believe the answer is:
at times
'now and again' is the definition.
(I've seen this before)
'employed by london-based newspaper' is the wordplay.
'employed by' becomes 'at' (employed at a certain job).
'london-based newspaper' becomes 'Times' (the Times of London).
'at'+'times'='AT TIMES'
(Other definitions for at times that I've seen before include "In the office" , "Every so often" , "Where some journalists work" , "employed by paper?" , "Not always" .)