Roaming free as feline, not caught by mammoth (2,5)
I believe the answer is:
at large
'roaming free' is the definition.
'feline not caught by mammoth' is the wordplay.
'feline' becomes 'cat' (I've seen this before).
'not' is a deletion indicator.
'caught' becomes 'c' (cricket abbreviation).
'by mammoth' becomes 'large' ('large' can be similar in meaning to 'mammoth'. I am not sure about the 'by' bit.**).
'cat' with 'c' taken out is 'at'.
'at'+'large'='AT-LARGE'
'as' acts as a link.
(Other definitions for at large that I've seen before include "Not confined, like escaped prisoner" , "Escaped; as a whole" , "generally" , "Glare at, being free and not confined" , "in a big way!" .)