Unpleasant films: one held up places of debauchery (7)
I believe the answer is:
nasties
'unpleasant films' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.
'one held up places of debauchery' is the wordplay.
'one' becomes 'an' (an apple is one apple).
'held up' is a reversal indicator.
'places of debauchery' becomes 'sties' (I can't explain this - if you can you should believe this answer much more).
'an' backwards is 'na'.
'na'+'sties'='NASTIES'
Can you help me to learn more?
(Another definition for nasties that I've seen is " obscene movies".)