Crossword Genius

Container holding bird and end­less jelly at the same time (4,5)

Ross

I believe the answer is:

then again

'at the same time' is the definition.
(both can mean 'on the other hand')

I don't understand how the rest of the clue works.

(Other definitions for then again that I've seen before include "From another point of view" , "however" , "still" .)

I've seen this clue in The Guardian.
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