Permitted nieces to play in lido, oddly (8)
I believe the answer is:
licensed
'permitted' is the definition.
(thesaurus)
'nieces to play in lido oddly' is the wordplay.
'to play' indicates an anagram.
'in' indicates putting letters inside.
'oddly' indicates alternate letters.
The alternate letters of 'lido' are 'ld'.
'nieces' anagrammed gives 'icense'.
'icense' going into 'ld' is 'LICENSED'.
(Other definitions for licensed that I've seen before include "Authorised officially" , "Officially sanctioned" , "Authorized officially" , "A - victualler is authorised to sell alcohol" , "Declines (anag.)" .)