Is American in sea badly treated? (7)
I believe the answer is:
misused
'badly treated?' is the definition.
(I've seen this before)
'is american in sea' is the wordplay.
'american' becomes 'US' (abbreviation for United States).
'in' is an insertion indicator.
'sea' becomes 'med' (abbreviation of Mediterranean).
'is'+'us'='isus'
'isus' inserted into 'med' is 'MISUSED'.
(Other definitions for misused that I've seen before include "Did exploit" , "Applied wrongly" , "wasted?" , "polluted, perhaps?" , "Falsely employed" .)