The most common and most likely answer to this crossword clue is the 5 letter word ABLED
A
B
L
E
D
Buddy explains!
The straight part
We know that "Robust" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case robust = abled.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 ABLED mean?
ABLED adjective- (in combination) Having a range of physical powers as specified.
- To make ready.
- To make capable; to enable.
- To dress.
- To give power to; to reinforce; to confirm.
- To vouch for; to guarantee.