Try to take off, but freak out (2,3)

I believe the answer is:

go ape

'freak out' is the definition.
(thesaurus)

'try to take off' is the wordplay.
'try' becomes 'go' (go is a kind of try).
'to take off' becomes 'ape' (I've seen this before).
'go'+'ape'='GO APE'

'but' acts as a link.

(Another definition for go ape that I've seen is " Throw a wobbly".)

I've seen this clue in The Guardian.

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