The non-attendance of Jack, the scene-shifter (7)
I believe the answer is:
absence
'the non-attendance' is the definition.
(I've seen this before)
'jack the scene-shifter' is the wordplay.
I cannot quite see how this works, but
'jack' could be 'ab' (both can mean a sailor) and 'ab' is found in the answer.
an anagram of 'scene' is 'sence' which is within the answer.
No letters remain.
This explanation may well be incorrect...
'of' acts as a link.
Can you help me to learn more?
(Other definitions for absence that I've seen before include "Want (of something)" , "Non-attendance" , "It may make the heart grow fonder" , "Failure to show" , "form of inattention?" .)