There's nothing more to be said, taking everything into account (3,4)
I believe the answer is:
all told
'taking everything into account' is the definition.
(I've seen this before)
'there's nothing more to be said' is the wordplay.
'there's' says to put letters next to each other.
'nothing more' becomes 'all' (I've seen this before).
'to be said' becomes 'told' (I've seen this before).
'all' put next to 'told' is 'ALL TOLD'.
(Other definitions for all told that I've seen before include "In total" , "book reading's finished?" , "Including everything" , "With everything or everyone taken into account" , "Altogether" .)