Blank out periods of time with ecstasy (5)
I believe the answer is:
erase
'blank out' is the definition.
(blank out can mean to erase or delete)
'periods of time with ecstasy' is the wordplay.
'periods of time' becomes 'eras' (an era is a period of time).
'with' means one lot of letters go next to another.
'ecstasy' becomes 'E' (informal term for the drug).
'eras'+'e'='ERASE'
(Other definitions for erase that I've seen before include "Delete" , "Remove recorded material" , "Blot out" , "Blank out" , "Remove all traces of" .)