Pleasant-sounding American entering phoney claim (7)
I believe the answer is:
musical
'pleasant-sounding' is the definition.
(I've seen this before)
'american entering phoney claim' is the wordplay.
'american' becomes 'US' (United States).
'entering' means one lot of letters goes inside another.
'phoney' is an anagram indicator.
'claim' is an anagram of 'mical'.
'us' put within 'mical' is 'MUSICAL'.
(Other definitions for musical that I've seen before include "Form of theatre" , "Show, with numbers" , "Song and dance show" , "Melodious" , "Melodic" .)