Number that has ten in, possibly, at the very end (6)
I believe the answer is:
ninety
'number' is the definition.
(ninety is a kind of number)
'ten in possibly at the very end' is the wordplay.
'possibly' is an anagram indicator.
'at' says to put letters next to each other.
'end' indicates one should take the final letters.
The final letter of 'very' is 'y'.
'ten'+'in'='tenin'
'tenin' with letters rearranged gives 'ninet'.
'ninet'+'y'='NINETY'
'that has' acts as a link.
(Other definitions for ninety that I've seen before include "Fourscore and ten" , "Minutes in a soccer game" , "6 x 3 x 5" , "Excellent percentage score" , "Minutes played in a football match" .)