The most common and most likely answer to this crossword clue is the 8 letter word APPETITE
I've seen this crossword clue in The Times
A
P
P
E
T
I
T
E
More clues leading to the result APPETITE
- Old man from the east with little desire for food?
- Bishop finally admitted to a slight thirst
- Dad's upset, having little enthusiasm
- The old man rises with very little desire to eat
- Father’s returned with little desire for food
- Pop upset delicate stomach
- Old man making climb has little desire
- Secretary going around with little desire for sex?
- Liking small area at the front with parking
- Retired old man with little desire for sex?
Buddy explains!

The straight part
We know that "enthusiasm" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case enthusiasm = appetite.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 APPETITE mean?
APPETITE noun- Desire to eat food or consume drink.
- Any strong desire; an eagerness or longing.
- The desire for some personal gratification, either of the body or of the mind.