Python Dataframe subtract value from one column from each list element of another column of a row

I have a dataframe. Column one has a list of numbers. Second column has average of list of numbers in column one. I need to create third column such that I subtract mean value from each of the elements of column one.

df = pd.DataFrame({'A':[[4.2,2.3,6.5,2.3],[4.1,5.3,6.5,3.8]]})
df['avg'] = df['A'].apply(lambda p: np.average(p))
df['a_avg' = df['A'].apply(lambda p: (np.array(p)-df['avg']).to_list()) 

Expected output:

df
           A               avg           a_avg
0     [4.2,2.3,6.5,2.3]   3.825        [0.375, -1.525, 2.675, -1.525]
1     [4.1,5.3,6.5,3.8]   4.925        [-0.825, 0.375, 1.575, -1.125]

I created column two for my clarity. if there is a way we can directly get column three from column one, that is also good. whats wrong with the code i have written?

>Solution :

..if there is a way we can directly get column three from column one,
that is also good.

I would do it this way :

df["a_avg"] = [[round(e - np.average(lst), 3) for e in lst] for lst in df["A"]]

Output :

print(df)

                      A                           a_avg
0  [4.2, 2.3, 6.5, 2.3]  [0.375, -1.525, 2.675, -1.525]
1  [4.1, 5.3, 6.5, 3.8]  [-0.825, 0.375, 1.575, -1.125]