Runs one sportsman finds more dangerous (7)
I believe the answer is:
riskier
'more dangerous' is the definition.
('risky' can be similar in meaning to 'dangerous')
'runs one sportsman' is the wordplay.
'runs' becomes 'r' (cricket abbreviation).
'one' becomes 'i' (Roman numeral).
'sportsman' becomes 'skier' (someone who skis).
'r'+'i'+'skier'='RISKIER'
'finds' acts as a link.
(Other definitions for riskier that I've seen before include "More likely to cause loss" , "More chancy" , "less safe" .)