Cryptic crossword clue
In gainful work, for sure 9

The most common and most likely answer to this crossword clue is the 9 letter word UNFAILING

I've seen this crossword clue in Financial Times
U
N
F
A
I
L
I
N
G

Buddy explains!

The straight part
We know that "for sure" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case for sure = unfailing.
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 UNFAILING mean?

UNFAILING adjective
  1. Inexhaustible
  2. Changeless
  3. Infallible

Latest crossword clues with full explanations