Entertainment as pretties become naughty … (10)
I believe the answer is:
'entertainment' is the definition.
(I've seen this before)
'as pretties become naughty' is the wordplay.
'become naughty' indicates an anagram.
'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?" .)