Disturbed rest with clap that's ghostly (8)
I believe the answer is:
spectral
'ghostly' is the definition.
(synonyms)
'disturbed rest with clap' is the wordplay.
'disturbed' is an anagram indicator (the order of letters is disturbed).
'with' says to put letters next to each other.
'rest' after 'clap' is 'claprest'.
'claprest' is an anagram of 'SPECTRAL'.
'that's' is the link.
(Other definitions for spectral that I've seen before include "Rap Celts for being ghostly" , "Of or like a ghost" , "Like a colourful band" , "Ghastly" , "Spooky" .)