What char does at night for unblemished record? (5,5)
I believe the answer is:
clean slate
'unblemished record?' is the definition.
(a clean slate is a record with no faults recorded)
'what char does at night' is the wordplay.
I cannot really see how this works, but
'at' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'for' acts as a link.
(Other definitions for clean slate that I've seen before include "making a fresh start?" , "good record" , "A record without dishonour" , "new start" .)