The most common and most likely answer to this crossword clue is the 11 letter word PERSEVERATE
I've seen this crossword clue in The Times
P
E
R
S
E
V
E
R
A
T
E
More clues leading to the result PERSEVERATE
Buddy explains!

The straight part
We know that "Return much" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case return much = perseverate.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 PERSEVERATE mean?
PERSEVERATE verb- (instransitive) To persist in doing something; to continue to repeat an action after the original stimulus has ended.
- To cause the perseveration of (a given reflex or response).