How's your father, mother, uncle and aunt? (9)
I believe the answer is:
relations
'how's your father mother' is the definition.
I can't tell whether this definition defines the answer.
'uncle and aunt?' is the wordplay.
'uncle' becomes 's' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'and' means one lot of letters go next to another.
'aunt?' becomes 'relation' (aunt is a kind of relation).
's' after 'relation' is 'RELATIONS'.
Can you help me to learn more?
(Other definitions for relations that I've seen before include "Sex" , "Family members" , "kinsfolk" , "Tale-telling" , "They're connected by blood or marriage" .)