The most common and most likely answer to this crossword clue is the 7 letter word GUERDON
G
U
E
R
D
O
N
Buddy explains!

The straight part
We know that "reward" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case reward = guerdon.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 GUERDON mean?
GUERDON noun- A reward, prize or recompense for a service; an accolade.
- To give such a reward to.