The most common and most likely answer to this crossword clue is the 7 letter word LANGUID
I've seen this crossword clue in Independent
L
A
N
G
U
I
D
More clues leading to the result LANGUID
- Listless, glad Uni is out
- Clock face twisted, split by gun thrown without much energy
- Weak local network? Good north of the border
- Slow PC network with short lead
- Scottish chap mostly seen in top lacking zip
- Listless learner given a northern mentor mostly
- Cover over most of Scottish county, being sluggish
- Lazy student with an abridged book
- Laid gun carelessly when relaxed
- Inland instrument not half listless
Buddy explains!

The straight part
We know that "sluggish" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sluggish = languid.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 LANGUID mean?
LANGUID adjective- Lacking enthusiasm, energy, or strength; drooping or flagging from weakness, fatigue, or lack of energy
- Heavy; dull; dragging; wanting spirit or animation; listless; apathetic.
- A languet in an organ (musical instrument).