Jack (lightweight) gets a shock (6)

I believe the answer is:

jounce

'a shock' is the definition.
(I know that shock can be written as jounce)

'jack lightweight' is the wordplay.
'jack' becomes 'J' (playing card abbreviation).
'lightweight' becomes 'ounce' (light unit of weight).
'j'+'ounce'='JOUNCE'

'gets' is the link.

(Another definition for jounce that I've seen is " Bump".)

I've seen this clue in The Guardian.

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