Unexpected visitor in winter trying to sell you something? (4,6)
I believe the answer is:
cold caller
'winter trying to sell you something?' is the definition.
I know nothing about this answer so I can't tell whether this works.
'unexpected visitor' is the wordplay.
'unexpected' becomes 'cold' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'visitor' becomes 'caller' (caller is a kind of visitor).
'cold'+'caller'='COLD CALLER'
'in' acts as a link.
(Another definition for cold caller that I've seen is " Person soliciting business without introduction".)