The most common and most likely answer to this crossword clue is the 5 letter word UNFIT
I've seen this crossword clue in Independent
U
N
F
I
T
More clues leading to the result UNFIT
- Out of shape squad drinking in France
- Force adopted by military group is not appropriate
- Inappropriate fine accepted by one
- Ill-equipped force brigade encircles
- Inappropriate female introduced to squad
- . Not able to have posh new suit
- Ineligible female included in squad
- Needing exercise, one circles a furlong
- Large body to go comfortably round, being out of shape
- Female in brigade failing physical education?
Buddy explains!

The straight part
We know that "Incompetent fellow trapped in kitchen cupboard? (5)/Incompetent" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case incompetent fellow trapped in kitchen cupboard? (5)/incompetent = unfit.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 UNFIT mean?
UNFIT verb- To make unfit; to render unsuitable, spoil, disqualify.
- Not fit; not having the correct requirements.
- Not fit, not having a good physical demeanor.