Alter it by breaking free (2,7)
I believe the answer is:
at liberty
'free' is the definition.
('at liberty' can be similar in meaning to 'free')
'alter it by breaking' is the wordplay.
'breaking' indicates anagramming the letters.
'alter'+'it'+'by'='alteritby'
'alteritby' is an anagram of 'AT LIBERTY'.
(Other definitions for at liberty that I've seen before include "Available" , "Not imprisoned" , "Free, not confined" .)