Complain about Bermuda triangle, lack of rain and date (7)

I believe the answer is:

grumble

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'complain' is the definition.
(I know that grumble is a type of complain)

I don't understand the rest of the clue.

(Other definitions for grumble that I've seen before include "Complain, be a grouch" , "Murmur with discontent" , "what Meldrew does" , "Moan" , "bitch" .)

I've seen this clue in the Sydney Morning Herald.

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