The most common and most likely answer to this crossword clue is the 13 letter word COMMEMORATION
I've seen this crossword clue in The Times
C
O
M
M
E
M
O
R
A
T
I
O
N
More clues leading to the result COMMEMORATION
Buddy explains!
The straight part
We know that "Keeping in mind" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case keeping in mind = commemoration.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
Crossword Answer definitions
COMMEMORATION noun- The act of commemorating; an observance or celebration to honor the memory of some person or event.
- That which serves the purpose of commemorating; a memorial.
- The specification of individual saints in the prayers for the dead; the great festival of the Oxford academic year, usually taking place on the third Wednesday after Trinity Sunday.