The most common and most likely answer to this crossword clue is the 8 letter word AIRDROPS
I've seen this crossword clue in The Daily Telegraph
A
I
R
D
R
O
P
S
More clues leading to the result AIRDROPS
Buddy explains!

The straight part
We know that "Supplies of aid" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case supplies of aid = airdrops.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 AIRDROPS mean?
AIRDROPS noun- The act of delivering goods, equipment, or personnel by dropping them from an aircraft in flight.
- To delivery goods, equipment, or personnel by dropping them from an aircraft in flight.