Foreign character turns up in the morning publication (5)
I believe the answer is:
gamma
'foreign character' is the definition.
(Greek letter)
'turns up in the morning publication' is the wordplay.
'turns up in' is a reversal indicator (I've seen 'turning up in' mean this).
'the morning' becomes 'am' (as in 12:00 AM).
'publication' becomes 'mag' (abbreviation for magazine).
'am'+'mag'='ammag'
'ammag' reversed gives 'GAMMA'.
(Other definitions for gamma that I've seen before include "Mediocre grade" , "Letter from Greece" , "A bit of Greek" , "The Greek g, third in alphabet" , "Greek letter G" .)