Welcome small bird’s class (4)

I believe the answer is:

aves

'bird's class' is the definition.
(zoological term for animals which are birds)

'welcome small' is the wordplay.
'welcome' becomes 'ave' (I've seen this before).
'small' becomes 's' (abbreviation - e.g. clothes size).
'ave'+'s'='AVES'

(Another definition for aves that I've seen is " Reverential salutations: class of vertebrates which comprises birds".)

I've seen this clue in The Times.

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