University official, expert, on cold hill (7)
I believe the answer is:
proctor
'university official' is the definition.
(I've seen this before)
'expert on cold hill' is the wordplay.
'expert' becomes 'pro' (I've seen this before).
'on' is a charade indicator (letters next to each other).
'cold' becomes 'c' (eg on taps).
'hill' becomes 'tor' (tor is a kind of hill).
'pro'+'c'+'tor'='PROCTOR'
(Other definitions for proctor that I've seen before include "Disciplinary officer" , "University official" , "University officer" , "University disciplinarian" , "College official" .)