"Therefore . . ." - Crossword Clue, Answer and Explanation

'therefore' is the definition.
(I know that therefore can be written as thus)

This is the entire clue.

(Other definitions for thus that I've seen before include "In this way" , "as indicated" , "an original Christmas gift" , "It follows" , "Therefore, hence" .)

I've seen this clue in The Wall Street Journal, the Universal, The Star Tribune, the Penny Press, the King Feature Syndicate, The Sun, The Guardian, The Mirror, the LA Times, the Newsday, The Times, The Telegraph, The New York Times, the Sydney Morning Herald, the USA Today, the Newsday.com, the Evening Standard, The Independent and The Washington Post.

'therefore' is the definition.
(I've seen this before)

This is all the clue.

(Other definitions for ergo that I've seen before include "Thus" , "Consequently" , "'Cogito, ---- sum'" , "so philosopher wrote in Latin" , "It follows" .)

I've seen this clue in The Wall Street Journal, the Universal, The Star Tribune, the Penny Press, the King Feature Syndicate, The Sun, The Guardian, The Mirror, the LA Times, the Newsday, The Times, The Telegraph, The New York Times, the Sydney Morning Herald, the USA Today, the Newsday.com, the Evening Standard, The Independent and The Washington Post.

'therefore' is the definition.
('so' can mean 'consequently' or 'therefore')

This is all the clue.

I've seen this clue in the King Feature Syndicate.

"Therefore . . ." (5)