Certainly ready to change after time in the recent past (9)
I believe the answer is:
yesterday
'the recent past' is the definition.
(I've seen this before)
'certainly ready to change after time' is the wordplay.
'certainly' becomes 'yes' (both can be used to answer in the affirmative).
'to change' indicates an anagram.
'after' says to put letters next to each other.
'time' becomes 't' (abbreviation).
'ready' is an anagram of 'erday'.
'erday' after 't' is 'terday'.
'yes'+'terday'='YESTERDAY'
'in' acts as a link.
(Other definitions for yesterday that I've seen before include "Song by Lennon/McCartney" , "has gone for ever!" , "of most recent history" , "Beatles hit - Thursday" , "some time in the past" .)