Altogether ultimately out of bounds (2,3)
I believe the answer is:
in all
'altogether' is the definition.
(I know that altogether can be written as in all)
'ultimately out of bounds' is the wordplay.
'ultimately' becomes 'finally' (synonyms).
'out of bounds' says to take the centre (the bounds or edges of the word are removed).
The central letters of 'finally' are 'IN ALL'.
(Other definitions for in all that I've seen before include "Summarising" , "Everything considered" , "With everything counted" , "totally" , "Completely" .)