Hide mistake somewhere in the field (9)

I believe the answer is:

coverslip

I'm a little stuck... Click here to teach me more about this clue!

'somewhere in the field' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.

'hide mistake' is the wordplay.
'hide' becomes 'cover' (covering is a kind of hiding).
'mistake' becomes 'slip' (a slip is a blunder or mistake).
'cover'+'slip'='COVERSLIP'

Can you help me to learn more?

(Another definition for coverslip that I've seen is " It clearly protects specimens".)

I've seen this clue in The Daily Express.

Want a hint initially instead of a full solution? Install my app