The most common and most likely answer to this crossword clue is the 3 letter word PLY
P
L
Y
More clues leading to the result PLY
Buddy explains!

The straight part
We know that "Keep working steadily" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case keep working steadily = ply.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 PLY mean?
PLY noun- A layer of material.
- A strand that, twisted together with other strands, makes up rope or yarn.
- Short for plywood.
- In two-player sequential games, a "half-turn" or a move made by one of the players.
- A condition, a state.
- To bend; to fold; to mould; to adapt, to modify; to change (a person's) mind, to cause (a person) to submit.
- To bend, to flex; to be bent by something, to give way or yield (to a force, etc.).
- A bent; a direction.
- To work at (something) diligently.
- To wield or use (a tool, a weapon, etc.) steadily or vigorously.
- To press upon; to urge persistently.
- To persist in offering something to, especially for the purpose of inducement or persuasion.
- To travel over (a route) regularly.
- To work diligently.
- To manoeuvre a sailing vessel so that the direction of the wind changes from one side of the vessel to the other; to work to windward, to beat, to tack.