The larder contains mature display (9)
I believe the answer is:
pageantry
'display' is the definition.
(I've seen this before)
'the larder contains mature' is the wordplay.
'the larder' becomes 'pantry' ('pantry' can be a synonym of 'larder').
'contains' indicates putting letters inside.
'mature' becomes 'age' ('age' can be a synonym of 'mature').
'pantry' going around 'age' is 'PAGEANTRY'.
(Other definitions for pageantry that I've seen before include "Show" , "Splendid display" , "Spectacle" .)