The man in love, American seen as odious (7)
I believe the answer is:
heinous
'odious' is the definition.
(thesaurus)
'the man in love american' is the wordplay.
'the man' becomes 'he'.
'love' becomes 'o' (In tennis, 'love' means 'zero').
'american' becomes 'us'.
'he'+'in'+'o'+'us'='HEINOUS'
'seen as' is the link.
(Other definitions for heinous that I've seen before include "Loathsome" , "Despicable" , "Utterly wicked" , "Dreadful" , "Iniquitous" .)