Laze around in endless postprandial rest? Most disgraceful! (9)

'most disgraceful' is the definition.

'laze around in endless postprandial rest?' is the wordplay.
'around' indicates an anagram.
'in' means one lot of letters goes inside another.
'endless' means to remove the last letter.
'postprandial rest?' becomes 'siesta' (rest taken after a meal).
'laze' with letters rearranged gives 'leaz'.
'siesta' with its final letter taken off is 'siest'.
'leaz' inserted inside 'siest' is 'SLEAZIEST'.