Historically, a son upset about a kiss (5)
I believe the answer is:
saxon
'historically a son upset about a kiss' is the definition.
I can't tell whether this defines the answer.
'a son upset about a kiss' is the wordplay.
'upset' indicates anagramming the letters.
'about' means one lot of letters goes inside another.
'a kiss' becomes 'x'.
'a'+'son'='ason'
'ason' with letters rearranged gives 'saon'.
'saon' placed around 'x' is 'SAXON'.
Can you help me to learn more?
(Other definitions for saxon that I've seen before include "Member of Germanic tribe settled in southern England after the Romans" , "old English style" , "Early invader of southern England" , "Member of old Germanic people" , "Ancient German" .)