English last to accept American transient (7)
I believe the answer is:
elusive
'transient' is the definition.
(I've seen this before)
'english last to accept american' is the wordplay.
'english' becomes 'e' (abbreviation).
'last' becomes 'live' ('live' can be a synonym of 'last'**).
'to accept' indicates putting letters inside.
'american' becomes 'us'.
'live' enclosing 'us' is 'lusive'.
'e'+'lusive'='ELUSIVE'
(Other definitions for elusive that I've seen before include "Sue about Levi, being shifty" , "Hard to grasp" , "Evil use (anag.)" , "Not easy to pin down" , "Evasive or intangible" .)