His many years of success in legal practise ........ didn't come out without challenges
Answer Details
The best word to complete the sentence would be "didn't come out without challenges" is "However".
The word "however" is commonly used to introduce a contrast or a contradiction to the previous statement, which makes it an appropriate choice in this sentence. It indicates that despite the success achieved in legal practice over many years, there were still challenges that had to be faced.
The other options could also fit in the sentence grammatically, but they wouldn't convey the intended meaning of a contradiction or contrast between the two parts of the sentence. For instance, "indeed" would be used to emphasize and confirm the truth of the statement made in the first part of the sentence. "But" would also introduce a contrast, but it would suggest a less strong opposition than "however". "In spite of all" would imply that there were challenges, but it wouldn't create the necessary contrast to the first part of the sentence.