Eccentric aunt and mum mostly showing period of maturity (6)
I believe the answer is:
autumn
'period of maturity' is the definition.
'autumn' can be an answer for 'period' (autumn is a kind of period). I am unsure of the 'of maturity' bit.
'eccentric aunt and mum mostly' is the wordplay.
'eccentric' indicates an anagram.
'and' says to put letters next to each other.
'mostly' means to remove the first letter.
'mum' with its first letter taken away is 'um'.
'aunt' after 'um' is 'umaunt'.
'umaunt' anagrammed gives 'AUTUMN'.
'showing' acts as a link.
Can you help me to learn more?
(Other definitions for autumn that I've seen before include "Browning happened then" , "Fall (over the pond?)" , "Fall for 33 across" , "Fall for Mrs Obama" , "October's season" .)