An American lawyer will accept a prisoner being such a snake (8)
I believe the answer is:
anaconda
'such a snake' is the definition.
(anaconda is a kind of snake)
'an american lawyer will accept a prisoner' is the wordplay.
'american lawyer' becomes 'da' (abbreviation for District Attorney).
'will accept' is an insertion indicator.
'prisoner' becomes 'con' (abbreviation for 'convict').
'an'+'da'='anda'
'a'+'con'='acon'
'anda' placed around 'acon' is 'ANACONDA'.
'being' is the link.
(Other definitions for anaconda that I've seen before include "Large water snake" , "1 of 21 [SNAKES]" , "Large semiaquatic snake" , "Aquatic snake" , "Strangler" .)