The most common and most likely answer to this crossword clue is the 6 letter word PRICED
I've seen this crossword clue in The Daily Telegraph
P
R
I
C
E
D
More clues leading to the result PRICED
Buddy explains!

The straight part
We know that "Estimated the value of" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case estimated the value of = priced.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 PRICED mean?
PRICED verb- To determine the monetary value of (an item); to put a price on.
- To pay the price of; to make reparation for.
- To set a price on; to value; to prize.
- To ask the price of.
- (in combination) Having a price of the kind specified.