The most common and most likely answer to this crossword clue is the 11 letter word REINSTATING
I've seen this crossword clue in The Sunday Telegraph
R
E
I
N
S
T
A
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G
Buddy explains!

The straight part
We know that "Putting back" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case putting back = reinstating.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 REINSTATING mean?
REINSTATING verb- To restore to a former position or rank.
- To bring back into use or existence; resurrect.