Got upset or had go at selfish driver (7)
I believe the answer is:
roadhog
'selfish driver' is the definition.
'roadhog' can be an answer for 'driver' (roadhog is a kind of driver). I'm unsure of the 'selfish' bit.
'got upset or had go' is the wordplay.
'got upset' is an anagram indicator (I've seen 'getting upset' mean this).
'or'+'had'+'go'='orhadgo'
'orhadgo' is an anagram of 'ROADHOG'.
'at' acts as a link.
Can you help me to learn more?
(Another definition for roadhog that I've seen is " Reckless driver".)