Not half charming claim (4)
I believe the answer is:
plea
'claim' is the definition.
'not half charming' is the wordplay.
'not half' means to take half the letters.
'charming' becomes 'pleasing' (similar in meaning).
'pleasing' with half the letters taken is 'PLEA'.
(Other definitions for plea that I've seen before include "Answer made by the accused to the charge" , "Urgent request" , "suit" , "Appeal - with bargaining?" , "Earnest appeal" .)