Monkey endlessly gambolling alongside grand Asian river (6)

I believe the answer is:

mekong

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'river' is the definition.
(Mekong is an example)

I cannot understand how the remainder of the clue works.

(Other definitions for mekong that I've seen before include "River and delta in southern Vietnam" , "The river flows through a large delta in Vietnam" , "River with vast delta in Vietnam" , "Asian river, flows into South China Sea" , "River flowing from Tibet to the South China Sea" .)

I've seen this clue in The Hindu.

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