One Conservative in English ship finding extreme cold (7)
I believe the answer is:
iciness
'extreme cold' is the definition.
(I've seen this before)
'one conservative in english ship' is the wordplay.
'one' becomes 'i' (Roman numeral).
'conservative' becomes 'C' (UK political abbreviation).
'english' becomes 'E' (abbreviation).
'ship' becomes 'SS' (prefix in ship names eg SS Great Britain).
'i'+'c'+'in'+'e'+'ss'='ICINESS'
'finding' acts as a link.
(Other definitions for iciness that I've seen before include "Hostile or cold nature" , "Unapproachability" , "Extreme hostility" , "Frigidity" , "Chill; reserve" .)