When email fails in the interim (9)
I believe the answer is:
meanwhile
'in the interim' is the definition.
(I've seen this before)
'when email fails' is the wordplay.
'fails' indicates anagramming the letters (a failed spelling).
'when'+'email'='whenemail'
'whenemail' is an anagram of 'MEANWHILE'.
(Other definitions for meanwhile that I've seen before include "simultaneously" , "For the moment" , "In the interim" , "On the other hand" , "in intervening period" .)