Climbers from India struggle on peak in Switzerland (5)
I believe the answer is:
ivies
'climbers' is the definition.
(ivies are climbing plants)
'india struggle on peak in switzerland' is the wordplay.
'india' becomes 'i' (phonetic alphabet: alpha, bravo, charlie etc.).
'struggle' becomes 'vie' (I've seen this before).
'on' means one lot of letters go next to another.
'peak in' indicates taking the first letters (in a down clue, the letter at the top of the word).
The first letter of 'switzerland' is 's'.
'i'+'vie'+'s'='IVIES'
'from' is the link.
(Other definitions for ivies that I've seen before include "Climbers" , "Climbing plants with evergreen leaves" , "Vines with evergreen leaves" .)