Diplomat's mother backing singer on road upset (10)
I believe the answer is:
ambassador
'diplomat's' is the definition.
(ambassador is a kind of diplomat)
'mother backing singer on road upset' is the wordplay.
'mother' becomes 'ma' (ma is a kind of mother).
'backing' is a reversal indicator.
'singer on' becomes 'bass' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'upset' indicates an anagram.
'ma' reversed gives 'am'.
'road' is an anagram of 'ador'.
'am'+'bass'+'ador'='AMBASSADOR'
Can you help me to learn more?
(Other definitions for ambassador that I've seen before include "diplomatic type" , "accredited diplomat" , "In a different case, he could be" , "Messenger" , "Foreign representative" .)