Slight loss of area from incomplete shield (6)
I believe the answer is:
insult
'slight' is the definition.
(I've seen this before)
'loss of area from incomplete shield' is the wordplay.
I cannot quite see how this works, but
'from' could be 'in' (I've seen this in other clues) and 'in' is present in the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for insult that I've seen before include "Affront, offend" , "Disrespectful remark" , "Hurtful and offensive remark" , "Cause offence to" , "Speak to or treat with disrespect" .)