Special article from Mont Blanc, capturing climb in good weather (8)
I believe the answer is:
sunshine
'good weather' is the definition.
(pleasant weather)
'special article from mont blanc capturing climb' is the wordplay.
'special' becomes 'S' (common abbreviation as in Special Air Service).
'article from mont blanc' becomes 'une' (French indefinite article -Mont Blanc is in France).
'capturing' means one lot of letters goes inside another.
'climb' becomes 'shin' (to shin can mean to climb up something).
'une' enclosing 'shin' is 'unshine'.
's'+'unshine'='SUNSHINE'
'in' is the link.
(Other definitions for sunshine that I've seen before include "Daily light and warmth" , "Ironic address (as of policeman to young offender)" , "Rays from source of light" , "''You are my ..., my only ...'' (song)" , "Is she nun out in the fine weather" .)