Lt. McNoban lost in French peak (4,5)
I believe the answer is:
'french peak' is the definition.
'mont blanc' can be an answer for 'peak' (Mont Blanc is an example). I'm not sure about the 'french' bit.
'lt mcnoban lost' is the wordplay.
'lost' is an anagram indicator.
'ltmcnoban' is an anagram of 'MONT BLANC'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for mont blanc that I've seen before include "Highest Alpine peak" , "Mountain in 6" , "Highest mountain in the?Alps" , "French Alps peak" , "peak form" .)