Mount hotly tipped when it runs (4)
I believe the answer is:
etna
'mount' is the definition.
(Etna is an example)
'hotly tipped when it runs' is the wordplay.
I cannot really see how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is located in the answer.
The remaining letters 'ena' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for etna that I've seen before include "Constant smoker" , "high peak" , "A feature of Sicily" , "Sicilian volcano" , "hole in the crust" .)