Go through a tidal flood (4)

I believe the answer is:

bore

I'm a little stuck... Click here to teach me more about this clue!

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

I don't understand the rest of the clue.

(Other definitions for bore that I've seen before include "pain from > drill" , "Tidal wave; drill" , "Drill or be tedious" , "Pierce - weary - tidal flood" , "Dull person; tidal wave" .)

I've seen this clue in The Irish Independent.

Want a hint initially instead of a full solution? Install my app