Plane takes irregular course to Himalayan state (5)
I believe the answer is:
nepal
'himalayan state' is the definition.
(I've seen this before)
'plane takes irregular course' is the wordplay.
'plane' anagrams to 'NEPAL'.
But, I'm not sure how this is indicated.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for nepal that I've seen before include "Asian kingdom" , "Plane country north-east of India" , "Small lake" , "Country in plane north-west of India" , "somewhere in Asia" .)