Porter maybe abandoning poet in mountainous region (5)
I believe the answer is:
ridge
'mountainous region' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'porter maybe abandoning poet' is the wordplay.
'porter maybe' becomes 'Cole' (musician Cole Porter).
'abandoning' indicates named letters should be taken away.
'poet' becomes 'Coleridge' (Samuel Taylor Coleridge, 1772-1834).
'coleridge' with 'cole' removed is 'RIDGE'.
'in' is the link.
Can you help me to learn more?
(Other definitions for ridge that I've seen before include "watershed ..." , "Long narrow natural elevation" , "Top of sloping roof" , "Narrow elevated strip" , "Highland area" .)