To agree, without exception (7)
I believe the answer is:
totally
'without exception' is the definition.
(I've seen this in another clue)
'to agree' is the wordplay.
'agree' becomes 'tally' (synonyms).
'to'+'tally'='TOTALLY'
(Other definitions for totally that I've seen before include "Clean" , "Completely, entirely" , "in every respect" , "Wholly" , "without reserve" .)