The most common and most likely answer to this crossword clue is the 5 letter word FINER
I've seen this crossword clue in Financial Times
F
I
N
E
R
Buddy explains!

The straight part
We know that "Comparatively sensitive" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case comparatively sensitive = finer.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 FINER mean?
FINER adjective- Senses referring to subjective quality.
- Senses referring to objective quality.
- Behind the batsman and at a small angle to the line between the wickets.
- Subtle; thin; tenuous.
- One who fines or purifies.