The most common and most likely answer to this crossword clue is the 7 letter word NURTURE
I've seen this crossword clue in The Times
N
U
R
T
U
R
E
More clues leading to the result NURTURE
- Key routine to manage raising?
- Rear enthusiast to cross river followed by another
- Upbringing having run true to form?
- With track race put back, athlete finally gets to train
- Raise northern river covering track heading west
- Upbringing having run true to form
- Somehow turn over flower to care for
- Training courses lifted the lid on education
- Training set up European with routine work
- Penniless, break out and dash back to mother
Buddy explains!

The straight part
We know that "to train" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case to train = nurture.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 NURTURE mean?
NURTURE noun- The act of nourishing or nursing; tender care
- That which nourishes; food; diet.
- The environmental influences that contribute to the development of an individual (as opposed to "nature").
- To nourish or nurse.
- (by extension) To encourage, especially the growth or development of something.