The sleep I have is disturbed (7)
I believe the answer is:
restive
'disturbed' is the definition.
Both the answer and definition are adjectives. Perhaps you can see an association between them that I can't see?
'the sleep i have' is the wordplay.
'the sleep' becomes 'rest' (synonyms).
'i have' becomes 'I've' (contraction of 'I have').
'rest'+'ive'='RESTIVE'
'is' acts as a link.
Can you help me to learn more?
(Other definitions for restive that I've seen before include "It veers around, resisting control" , "Uneasy, nervous" , "Unable to keep still" , "Impatient - jumpy" , "Unsettled" .)