Type of number (7)
I believe the answer is:
ordinal
'type of number' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ordinal that I've seen before include "First, for One" , "It shows your place" , "Of position in series; service book (hist.)" , "First and second, say" , "(Of numbers) first or second, perhaps" .)