Wrong to get in front of ship's wave (6)

I believe the answer is:

billow

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But I can't explain it at all! Could you help me understand?

(Other definitions for billow that I've seen before include "Swell out in the wind" , "Surge" , "Swell out (as a sail)" , "Swell out, as a flag" , "Rise or roll like wave" .)

I've seen this clue in The Sun.

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