Mostly icy mountain cuts through Australian state (8)
I believe the answer is:
victoria
'australian state' is the definition.
(Victoria is an example)
'mostly icy mountain cuts through' is the wordplay.
'mostly icy' becomes 'ic' (I can't justify this - if you can you should give a lot more credence to this answer).
'mountain' becomes 'tor'.
'cuts' is an insertion indicator (some letters cut their way into a word).
'through' becomes 'via' (via means going through).
'ic'+'tor'='ictor'
'ictor' placed within 'via' is 'VICTORIA'.
Can you help me to learn more?
(Other definitions for victoria that I've seen before include "Queen, Australian state and plum" , "Monarch" , "one wasn't amused" , "Mrs Beckham" , "She falls in Africa" .)