Love trendy coats Oscar's wearing (7)
I believe the answer is:
erosion
'wearing' is the definition.
(I know that wearing can be written as erosion)
'love trendy coats oscar's' is the wordplay.
'love' becomes 'eros' (Greek god of love).
'trendy' becomes 'in' ('in' can mean fashionable).
'coats' means one lot of letters goes inside another.
'oscar' becomes 'O' (phonetic alphabet: alpha, bravo, charlie etc.).
'in' going around 'o' is 'ion'.
'eros'+'ion'='EROSION'
(Other definitions for erosion that I've seen before include "A wearing away as of rock by water" , "being eaten away" , "Wearing away (of soil, rocks etc)" , "Process of wear" , "Abrasion" .)