Swell sky is not seen fully (5)

I believe the answer is:

heave

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

I don't understand the rest of the clue.

(Other definitions for heave that I've seen before include "past Hove" , "Throw; haul by rope (naut.)" , "Produce (a sigh); retch" , "cast like this" , "Haul - retch" .)

I've seen this clue in The Hindu.

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