American in school trains here! (6)
I believe the answer is:
euston
'trains here' is the definition.
(I've seen this before)
'american in school' is the wordplay.
'american' becomes 'US' (United States).
'in' is an insertion indicator.
'school' becomes 'eton' (famous UK public school).
'us' placed inside 'eton' is 'EUSTON'.
(Other definitions for euston that I've seen before include "No suet (anag)" , "London mainline station" , "train here?" , "training objective?" , "London rail terminus" .)