Small bottle, as originally described by Collins? (5)
I believe the answer is:
phial
'small bottle' is the definition.
(a phial or vial is a small bottle)
'as originally described by collins?' is the wordplay.
'originally' suggests taking the first letters.
'described by' means one lot of letters goes inside another (to describe can mean to form an outline).
'collins?' becomes 'Phil' (musician Phil Collins).
The first letter of 'as' is 'a'.
'a' placed into 'phil' is 'PHIAL'.
(Other definitions for phial that I've seen before include "Small glass bottle for perfume or medicine" , "Small flask" , "Source of medicine" , "Small bottle for potions etc" , "Ampoule" .)