Begin at steep canyon and finish with climb? (6)
I believe the answer is:
ascend
'climb?' is the definition.
(climb can mean to ascend or go up)
'begin at steep canyon and finish' is the wordplay.
'begin' suggests taking the first letters.
'and' means one lot of letters go next to another.
'finish' becomes 'end' (come to an end).
The initial letters of 'at steep canyon' is 'asc'.
'asc'+'end'='ASCEND'
'with' acts as a link.
(Other definitions for ascend that I've seen before include "Travel upwards" , "Come up" , "Move upward" , "Take off" , "Gain altitude" .)