Really hard work to get article's strapline (6)
I believe the answer is:
Here is my best explanation:
'strapline' is the definition.
'really hard work to get article's' is the wordplay.
'really hard work' becomes 'slog' (slog can informally mean hard or boring work).
'to get' means one lot of letters go next to another.
'article' becomes 'an' (indefinite article).