Important to welcome news editor portraying President (7)
I believe the answer is:
kennedy
'president' is the definition.
(I've seen this before)
'important to welcome news editor' is the wordplay.
'important' becomes 'key' (similar in meaning).
'to welcome' indicates putting letters inside (in sense of 'inviting in').
'news' becomes 'nn' (I've seen this in other clues).
'editor' becomes 'ed'.
'nn'+'ed'='nned'
'key' placed around 'nned' is 'KENNEDY'.
'portraying' is the link.
(Other definitions for kennedy that I've seen before include "Catholic US president" , "US president assassinated in Dallas" , "Nigel -, Br. violinist" , "Youngest US President" , "brothers Jack and Bobby both shot" .)