The most common and most likely answer to this crossword clue is the 8 letter word MINUTELY
I've seen this crossword clue in The Daily Telegraph
M
I
N
U
T
E
L
Y
More clues leading to the result MINUTELY
Buddy explains!

The straight part
We know that "Using a fine-tooth comb/every sixty seconds?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case using a fine-tooth comb/every sixty seconds? = minutely.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 MINUTELY mean?
MINUTELY adjective- Happening every minute; continuing; unceasing.
- With attention to tiny details.
- On a minute scale.