The most common and most likely answer to this crossword clue is the 7 letter word KICKING
I've seen this crossword clue in Financial Times
K
I
C
K
I
N
G
Buddy explains!
The straight part
We know that "Giving up/putting the boot in" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case giving up/putting the boot in = kicking.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 KICKING mean?
KICKING verb- To strike or hit with the foot or other extremity of the leg.
- To make a sharp jerking movement of the leg, as to strike something.
- To direct to a particular place by a blow with the foot or leg.
- (with "off" or "out") To eject summarily.
- To forcibly remove a participant from an online activity.
- To overcome (a bothersome or difficult issue or obstacle); to free oneself of (a problem).
- To move or push suddenly and violently.
- (of a firearm) To recoil; to push by recoiling.
- To attack (a piece) in order to force it to move.
- To accelerate quickly with a few pedal strokes in an effort to break away from other riders.
- To show opposition or resistance.
- To work a press by impact of the foot on a treadle.
- To die.
- The action of the verb to kick.
- A violent assault involving repeated kicks.
- A great loss or defeat; licking.
- Terrific, great (of clothes) smart, fashionable.
- Alive, active (especially in the phrase alive and kicking).
- (of a party or event) Actively ongoing and enjoyable.