In each of the other three answers of the second type, the definition is given as a single word in another clue. This word is redundant in the sense that you can remove it and the clue then makes perfect sense, with a definition and wordplay.
In this case, the thematic answer is part in the clue you mention, but it is not a single word and it is not redundant. That is my issue. If there is no consistency in the way in which the definitions work, I think this is a weakness.