The most common and most likely answer to this crossword clue is the 12 letter word APPRECIATION
I've seen this crossword clue in The Times
A
P
P
R
E
C
I
A
T
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O
N
Buddy explains!

The straight part
We know that "Liking/understanding/growth" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case liking/understanding/growth = appreciation.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.
What does APPRECIATION mean?
APPRECIATION noun- A fair valuation or estimate of merit, worth, weight, etc.; recognition of excellence.
- Accurate perception; true estimation.
- A rise in value.