Climber picked up medical supply (3)
I believe the answer is:
ivy
'climber' is the definition.
(ivy is a climbing plant)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for ivy that I've seen before include "Hedera helix" , "Vine with evergreen leaves" , "Climbing-plant" , "Girl" , "Poisonous plant" .)