The most common and most likely answer to this crossword clue is the 5 letter word PUKKA
I've seen this crossword clue in The Guardian
P
U
K
K
A
More clues leading to the result PUKKA
- Contract’s sound, done perfectly
- Genuine broadcasting contract
- A couple of kings happy to retire for real
- Perfectly constructed contract, according to auditor
- Genuine Dad crossing this country park finally
- Excellent posh weekends during every year
- Authentic sound coming from cockle
- Respectable European country having King within a year
- Mention of wrinkle being genuine
- Genuine screw-up by the sound of it
Buddy explains!

The straight part
We know that "Perfectly constructed" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case perfectly constructed = pukka.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 PUKKA mean?
PUKKA adjective- (originally South Asia) Genuine or authentic; hence of behaviour: correct, socially acceptable or proper.
- Superior or of high quality; first-class.
- Excellent, fantastic, great.