The most common and most likely answer to this crossword clue is the 7 letter word SLAVISH
I've seen this crossword clue in Financial Times
S
L
A
V
I
S
H
More clues leading to the result SLAVISH
- Prodigal son’s first to be submissive
- Submissive like a mid-European
- Submissive prodigal son comes first
- Servile as prodigal son, to begin with
- Abject prodigal son travelling to point of origin
- of something extravagant but unoriginal
- Prodigal son before getting servile
- Abjectly servile son's over-indulgent
- Submissive, like an East European?
- Obsequious European is given heroin
Buddy explains!

The straight part
We know that "submissive" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case submissive = slavish.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 SLAVISH mean?
SLAVISH adjective- In the manner of a slave; abject.
- (Of a copy) utterly faithful; totally lacking originality or creativity.