Morphing is for green aliens (10)

I believe the answer is:

foreigners

'aliens' is the definition.
(old-fashioned term for foreigners)

'morphing is for green' is the wordplay.
'morphing' is an anagram indicator (I've seen 'morph' mean this (the letters morph into a new form)).
'is'+'for'+'green'='isforgreen'
'isforgreen' with letters rearranged gives 'FOREIGNERS'.

I've seen this clue in The Telegraph.

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