Person who's expected endless sex badly beaten outside (8)
I believe the answer is:
absentee
'person' is the definition.
(absentee is a kind of person)
'endless sex badly beaten outside' is the wordplay.
'endless' means to remove the last letter.
'badly' is an anagram indicator (letters in the wrong order).
'outside' means one lot of letters goes inside another (some letters go outside others).
'sex' with its final letter taken off is 'se'.
'beaten' with letters rearranged gives 'abntee'.
'se' put inside 'abntee' is 'ABSENTEE'.
'who's expected' acts as a link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for absentee that I've seen before include "Someone not present" , "He's not here!" , "One who stays away" , "Missing person" , "One is not present when required" .)