The most common and most likely answer to this crossword clue is the 9 letter word CAST-IRON
I've seen this crossword clue in Financial Times
C
A
S
T
-
I
R
O
N
More clues leading to the result CAST-IRON
- Very strong players getting support of press
- Heavy metal players chased by press
- Absolutely reliable cold wine initially ready, or not?
- Sort of alibi that has not been forged
- After college moving on will be hard
- It’s hard for Tory keeping awake
- Unassailable study about being on the move
- M. le Président, missing mother, drinks fizz to become resolute
- Reliable players at club
Buddy explains!

The straight part
We know that "Absolutely reliable" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case absolutely reliable = cast-iron.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 CAST-IRON mean?
CAST-IRON noun- A hard and brittle, but strong, alloy of iron, carbon, and silicon, formed by casting in a mould.
- Made of cast iron.
- Durable; tough; resiliant.
- Inflexible or without exception.