The most common and most likely answer to this crossword clue is the 10 letter word THIRD-RATE
I've seen this crossword clue in The Times
T
H
I
R
D
-
R
A
T
E
More clues leading to the result THIRD-RATE
- Inferior rider that needs training
- That rider tumbling is mediocre
- Dither uneasily about wretch of poor quality
- After interval, judge is indifferent
- Inferior article about one on road with informer
- That rider is shaky, not much good
- Bad informer in dreadful dither
- Ground that rider regarded as poor
- Poor ‘rithmetic perhaps later discovered
Buddy explains!

The straight part
We know that "Inferior" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case inferior = third-rate.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 THIRD-RATE mean?
THIRD-RATE noun- A British ship-of-the-line with 64 to 80 guns divided across two gun decks.
- Of lesser value or quality than second-rate.
- Describing a British ship-of-the-line with 64 to 80 guns divided across two gun decks.