The most common and most likely answer to this crossword clue is the 3 plus 4 letter word POT LUCK
I've seen this crossword clue in The Daily Telegraph
P
O
T
L
U
C
K
Buddy explains!
The straight part
We know that "Whatever’s available" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case whatever’s available = pot luck.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 POT LUCK mean?
POT LUCK noun- A meal, especially one offered to a guest, consisting of whatever food is available.
- (by extension) Whatever is available in a particular situation.
- (originally Canada) A shared meal consisting of whatever guests have brought (sometimes without prior arrangement); a potlatch; also, a dish of food brought to such a meal.
- The last draft or portion of an alcoholic beverage in a pot or other drinking vessel.