Like some schooldays of the past (3)
I believe the answer is:
old
'the past' is the definition.
(old is a kind of past)
'like some schooldays' is the wordplay.
'OLD' is hidden within the letters.
However, I'm unsure how this is indicated.
'of' acts as a link.
Can you help me to learn more?
(Other definitions for old that I've seen before include "Wild clematis" , "Elderly" , "Much-used" , "Former, previous" , "out of the ark" .)