Before today, author Sinclair seen with pained expression (2,2,3)
I believe the answer is:
up to now
'before today' is the definition.
'author sinclair seen with pained expression' is the wordplay.
'author sinclair' becomes 'upton' (Upton Sinclair the American writer).
'seen with' is a charade indicator (letters next to each other).
'pained expression' becomes 'ow' (exclamation of pain).
'upton'+'ow'='UP TO NOW'
(Other definitions for up to now that I've seen before include "Hitherto" , "So far" .)