Cryptic crossword clue
Dirty location near Heathrow almost changed finally 7

The most common and most likely answer to this crossword clue is the 7 letter word STAINED

I've seen this crossword clue in The Daily Telegraph
S
T
A
I
N
E
D

Buddy explains!

The straight part
We know that "Dirty" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case dirty = stained.
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 STAINED mean?

STAINED verb
  1. To discolour.
  2. To taint or tarnish someone's character or reputation
  3. To coat a surface with a stain
  4. To become stained; to take a stain.
  5. To treat (a microscopic specimen) with a dye, especially one that dyes specific features
  6. To cause to seem inferior or soiled by comparison.
STAINED adjective
  1. Having a stain
  2. Coloured by adding a pigment

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