What does the cryptic crossword clue "Suffered, so gained redress (8)" mean?

The definition is "Suffered,". The wordplay uses an anagram. anagram of SO + GAINED = AGONISED; definition: "Suffered," The answer is AGONISED.

Suffered, so gained redress (8)

Guardian Cryptic #25785 | 11 Across | 2012-11-05 flower