The first mate takes the others for a tough climb (7)
I believe the answer is:
everest
'a tough climb' is the definition.
The answer and definition can be both natural objects as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'the first mate takes the others' is the wordplay.
'the first mate' becomes 'eve' (Adam's mate in the Bible).
'takes' says to put letters next to each other.
'the others' becomes 'rest' (eg the rest of a group).
'eve'+'rest'='EVEREST'
'for' acts as a link.
Can you help me to learn more?
(Other definitions for everest that I've seen before include "Highest Himalayan mountain" , "The highest mountain of all (7)" , "Mountain named after a British surveyor general of India" , "High peak" , "One conquered in 1953" .)