A number after a new hip flask (5)
I believe the answer is:
phial
'flask' is the definition.
(I have seen 'Small flask ' mean 'phial' so perhaps 'flask' could also mean 'phial')
'a number after a new hip' is the wordplay.
'number' becomes 'l' (L is an example).
'after' says to put letters next to each other.
'a new' indicates an anagram.
'hip' anagrammed gives 'phi'.
'a'+'l'='al'
'al' put after 'phi' is 'PHIAL'.
(Other definitions for phial that I've seen before include "Small glass bottle for perfume or medicine" , "Small bottle for potions etc" , "Small bottle (containing a drug)" , "Small flask" , "Source of medicine" .)