Wake, interrupting one's sleep, and check (9)
I believe the answer is:
restraint
'check' is the definition.
(I've seen this before)
'wake interrupting one's sleep and' is the wordplay.
I cannot quite see how this works, but
'sleep' could be 'rest' (synonyms) and 'rest' is located in the answer.
'and' could be 'n' (common abbreviation for 'and') and 'n' is present in the answer.
'one' could be 'i' (Roman numeral) and 'i' is found in the answer.
The remaining letters 'rat' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for restraint that I've seen before include "Self-control" , "Limiting device" , "Reserve" , "Check" , "It keeps someone or something under control" .)