Collected tropical medicine bottles (4)
I believe the answer is:
calm
'collected' is the definition.
(I've seen this before)
'tropical medicine bottles' is the wordplay.
'bottles' indicates a hidden word (bottling is a kind of containing).
'CALM' is hidden within 'tropical medicine'.
(Other definitions for calm that I've seen before include "Peaceful, undisturbed" , "Composed or free from storms" , "Self-possessed" , "'After a storm comes a ....'" , "Pacific" .)