The most common and most likely answer to this crossword clue is the 3 plus 3 letter word RAN DRY
R
A
N
D
R
Y
More clues leading to the result RAN DRY
- To west of railway, river also stopped flowing
- Stopped spouting rubbish, primarily, with year in retirement
- Hot over river — what it did?
- Was completely used to feeling lustful about Romeo
- Currency run on yen drained reserves
- Across verges of rockery river stopped flowing
- King getting amorous outside was exhausted
Buddy explains!

The straight part
We know that "was exhausted" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case was exhausted = ran dry.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.