Current offer to absorb phone company inside another (3,4)

I believe the answer is:

ebb tide

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

I cannot understand how the rest of the clue works.

(Other definitions for ebb tide that I've seen before include "Decline in sea level" , "Retreat of the sea" , "It's on the way out" , "Sea's outflow" , "Outgoing sea flow" .)

I've seen this clue in The Times.

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