I think we all agree that the answer isn't a 13 letter word but 4 words starting "well I never" which is definitely an exclamation of surprise, which I agree is looking favourite, My quandary is the last word (-I-), which has been reckoned to be (did), I agreed with this at first, but on further thought, I have come to a different result. As 'well i never did' sounds perfectly plausable, I think that as the word 'did' appears in the clue, and Times standard clues don't follow the practise of words appearing in the clue and answer, then could it be 'Well I never win' as to excel is to do better,and Do better is synonymous with winning? Tell me what you think.