Complain when area’s width is cut (4)
I believe the answer is:
mown
'is cut' is the definition.
(past tense of 'mow')
'complain when area's width' is the wordplay.
I cannot quite see how this works, but
'width' could be 'w' (abbreviation in geometry) and 'w' is found in the answer.
'when' could be 'on' (I've seen this in other clues) and 'on' is present in the remaining letters.
A single letter 'm' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for mown that I've seen before include "Cut down with a blade" , "(Of grass) cut" , "Block of cast metal" .)