Creatures coming from sea -- America beginning to shoot (7)

I believe the answer is:

medusas

'creatures' is the definition.
(medusa is a type of jellyfish)

'sea america beginning to shoot' is the wordplay.
'sea' becomes 'med' (abbreviation of Mediterranean).
'america' becomes 'usa' (synonyms).
'beginning to' says to take the initial letters.
The first letter of 'shoot' is 's'.
'med'+'usa'+'s'='MEDUSAS'

'coming from' is the link.

(Another definition for medusas that I've seen is " jellyfish".)

I've seen this clue in The Telegraph.

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