Space mission souvenir display behind tip (8)

I believe the answer is:

moonrock

'space mission souvenir' is the definition.
(souvenir brought back from the moon)

'display behind tip' is the wordplay.
'display behind' becomes 'moon' (moon can mean to show one's bottom).
'tip' becomes 'rock' (both can mean to wobble or tilt).
'moon'+'rock'='MOONROCK'

(Another definition for moonrock that I've seen is " Substance brought back by Apollo missions".)

I've seen this clue in The Guardian.

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