Fruity sort holding close upper-class swinger (8)
I believe the answer is:
pendulum
'swinger' is the definition.
(something which swings)
'fruity sort holding close upper-class' is the wordplay.
'fruity sort' becomes 'plum' (I can't explain this - if you can you should believe this answer much more).
'holding' means one lot of letters goes inside another.
'close' becomes 'end' (close can mean to end or finish).
'upper-class' becomes 'u' (similar in meaning).
'end'+'u'='endu'
'plum' going around 'endu' is 'PENDULUM'.
Can you help me to learn more?
(Other definitions for pendulum that I've seen before include "Swinging device used to regulate clock" , "Nude lump (anag)" , "It swings to and fro as in old clock" , "A swinging weight as in old clock" , "Lead swinging" .)