Stretch inside the long atelier (8)

I believe the answer is:

elongate

'stretch' is the definition.
(to elongate is to stretch out)

'inside the long atelier' is the wordplay.
'inside' indicates a hidden word.
'ELONGATE' is hidden within 'the long atelier'.

(Other definitions for elongate that I've seen before include "stretcher will do!" , "Stretch lengthways" , "Spread" , "Draw out" , "grow further" .)

I've seen this clue in The Telegraph.

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