Blank tape containing nothing (4)
I believe the answer is:
void
'blank' is the definition.
(thesaurus)
'tape containing nothing' is the wordplay.
'tape' becomes 'vid' (short for videotape).
'containing' means one lot of letters goes inside another.
'nothing' becomes 'o' (looks like zero - 0).
'vid' placed around 'o' is 'VOID'.
(Other definitions for void that I've seen before include "Empty space or vacuum" , "Null and empty" , "Gap, absence" , "Nullify" , "Free" .)