The most common and most likely answer to this crossword clue is the 5 plus 4 letter word LEMON SOLE
I've seen this crossword clue in The Daily Telegraph
L
E
M
O
N
S
O
L
E
More clues leading to the result LEMON SOLE
- Fish - reject one under a foot
- Menu item needs no Moselle in cooking
- Fish and fruit wonderful in Spain
- Someone swimming around lake east of Luxembourg could be a swimmer
- Grilled dish needs no Moselle in cooking
- Fish something worthless on its own?
- Charlie’s word of approval for fish dish
- Fruit? Only fish
- Fish and fruit only
- Dish only seen after fruit?
Buddy explains!

The straight part
We know that "fish" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case fish = lemon sole.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.