Great lad, almost entirely unruly, free from jail (2,5)
I believe the answer is:
at large
'free from jail' is the definition.
(at large means free or evading capture)
'great lad almost entirely unruly' is the wordplay.
'almost entirely' means to remove the last letter (most but not all of the word).
'unruly' indicates anagramming the letters.
'great'+'lad'='greatlad'
'greatlad' with its last letter taken off is 'greatla'.
'greatla' with letters rearranged gives 'AT-LARGE'.
(Other definitions for at large that I've seen before include "Glare at, being free and not confined" , "Escaped, not captured" , "Free like escaped convict" , "General on the loose" , "Escaped; as a whole" .)