The most common and most likely answer to this crossword clue is the 9 letter word COMMUTING
I've seen this crossword clue in The Daily Telegraph
C
O
M
M
U
T
I
N
G
Buddy explains!
The straight part
We know that "Training regularly" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case training regularly = commuting.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 COMMUTING mean?
COMMUTING verb- To exchange substantially; to abate but not abolish completely, a penalty, obligation, or payment in return for a great, single thing or an aggregate; to cash in; to lessen
- Of an operation, to be commutative, i.e. to have the property that changing the order of the operands does not change the result.
- To regularly travel from one's home to one's workplace or school, or vice versa.
- To journey, to make a journey
- Travel between home and workplace
- Travel by public transportation such as by jeepney
- Causing, or involved in commutation