Calling son a donkey perhaps upset mother and pa (8)
I believe the answer is:
metaphor
'calling son a donkey' is the definition.
I can't tell whether this definition defines the answer.
'upset mother and pa' is the wordplay.
'upset' indicates anagramming the letters.
'and' is a charade indicator (letters next to each other).
'mother' after 'pa' is 'pamother'.
'pamother' with letters rearranged gives 'METAPHOR'.
'perhaps' acts as a link.
Can you help me to learn more?
(Other definitions for metaphor that I've seen before include "7/16 [FIGURE OF SPEECH]" , "To hamper, badly, a figure of speech" , "Top harem is a figure of speech" , "Captain of industry, eg" , "Expression where something is described as if it really is what it merely resembles" .)