An American backed importing a Finnish bath (5)
I believe the answer is:
sauna
'finnish bath' is the definition.
(I've seen this in another clue)
'an american backed importing a' is the wordplay.
'american' becomes 'us' (abbreviation for United States).
'backed' shows that the letters should be reversed in order.
'importing' indicates putting letters inside.
'an'+'us'='anus'
'anus' written backwards gives 'suna'.
'suna' placed around 'a' is 'SAUNA'.
(Other definitions for sauna that I've seen before include "Very hot room for cleansing, of Finnish origin" , "Type of bath" , "Scandinavian hot room for cleansing oneself" , "Finnish-style bath" , "Steam-bath" .)