Coming in ungrammatically is delightful (10)
I believe the answer is:
entrancing
I believe this clue is a double definition.
'coming in ungrammatically' is the first definition.
('entrancing' could mean making an entrance)
'delightful' is the second definition.
(I've seen this before)
'is' is the link.
(Other definitions for entrancing that I've seen before include "Bewitching" , "Delightful" .)