The most common and most likely answer to this crossword clue is the 3 plus 6 letter word TIN OPENER
I've seen this crossword clue in The Guardian
T
I
N
O
P
E
N
E
R
More clues leading to the result TIN OPENER
- Device no writer put in line
- Can batsman be Cook’s assistant?
- What cook may use with starter of tempura in batter?
- Gadget unable to write in a line
- Can starter be produced in the kitchen?
- Can a beginner operate this kitchen equipment?
- Kitchen utensil can undo even beers
- Can one holding drill start to repair a kitchen utensil?
- One’s turned to get fare, with negative reaction by number in row
- T for tea-time tool, perhaps?
Buddy explains!

The straight part
We know that "What cook may use" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case what cook may use = tin opener.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 TIN OPENER mean?
TIN OPENER noun- A can opener