Spell 'elasticity' (7)

I believe the answer is:

stretch

I believe this is a double definition.

'spell' is the first definition.
(I've seen this before)

'elasticity' is the second definition.
(stretch is a kind of elasticity)

(Other definitions for stretch that I've seen before include "time at Pentonville?" , "Make demands on; continuous expanse" , "time spent in jail" , "Draw out" , "having just woken up?" .)

I've seen this clue in The Telegraph.

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