Entertainment as pretties become naughty … (10)
I believe the answer is:
striptease
'entertainment' is the definition.
(I've seen this before)
'as pretties become naughty' is the wordplay.
'become naughty' indicates an anagram.
'as'+'pretties'='aspretties'
'aspretties' is an anagram of 'STRIPTEASE'.
(Other definitions for striptease that I've seen before include "performance taking off" , "Sort of entertainment" , "Revelatory performance" , "adult show" , "that calls for gradual exposure?" .)