Putting tea, say, in small bottle is essential (5)
I believe the answer is:
vital
'essential' is the definition.
(similar in meaning)
'putting tea say in small bottle' is the wordplay.
I cannot quite understand how this works, but
'tea' could be 't' (I've seen this in other clues) and 't' is found in the answer.
'bottle' could be 'vial' (vial is a kind of bottle) and 'vial' is found within the leftover letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'is' acts as a link.
Can you help me to learn more?
(Other definitions for vital that I've seen before include "Essential to life or critically important" , "Desperately important" , "Absolutely necessary or life-giving" , "Spirited" , "Imperative" .)