The most common and most likely answer to this crossword clue is the 5 letter word SHREW
I've seen this crossword clue in The Guardian
S
H
R
E
W
More clues leading to the result SHREW
- Scold one that eats insects
- Vixen showing cunning endlessly
- Mouse-like creature playfully tamed?
- Vixen, cunning no end
- Mean-spirited woman takes hour in work with needle
- Share of lavish reward for Kate?
- Speech containing nothing sounding like regret for following 1
- Keep quiet about wife, she’s bad-tempered
- Nag mouse-like creature
- Mammal, foxy dropping tail
Buddy explains!

The straight part
We know that "Nag/mouse-like creature" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case nag/mouse-like creature = shrew.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 SHREW mean?
SHREW noun- Any of numerous small, mouselike, chiefly nocturnal, mammals of the family Soricidae (order Soricomorpha).
- Certain other small mammals that resemble true shrews (order Soricomorpha).
- An ill-tempered, nagging woman: a scold.
- To beshrew; to curse.