American former partner wearing brown (5)
I believe the answer is:
texan
'american' is the definition.
(Texan is an example)
'former partner wearing brown' is the wordplay.
'former partner' becomes 'ex'.
'wearing' is an insertion indicator.
'brown' becomes 'tan' (tan is a kind of brown).
'ex' put within 'tan' is 'TEXAN'.
(Other definitions for texan that I've seen before include "One from SW USA" , "From a large US state" , "Dallas resident?" , "One from south-west USA" , "Relating to a US state" .)