The most common and most likely answer to this crossword clue is the 1 plus 4 plus 2 plus 3 plus 3 letter word A SHOT IN THE ARM
I've seen this crossword clue in The Times
A
S
H
O
T
I
N
T
H
E
A
R
M
More clues leading to the result A SHOT IN THE ARM
- When sweaty, endless serving tonic
- As sexy nurses can get married, it's stimulating
- Running the marathon is something invigorating!
- Running the marathon is quite a tonic
- Booster, perhaps?
- Boost area this month with reinvigoration
- Injury boost?
- Some uplift when sweltering and not quite ready to fight?
- Boost run-down area this month
- Booster injection
Buddy explains!
The straight part
We know that "tonic" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case tonic = a shot in the arm.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.