Funny, glassy-looking substance in a mountain location (7)
I believe the answer is:
'funny' is the definition.
(I know that funny can be written as comical)
'glassy-looking substance in a mountain location' is the wordplay.
I cannot really see how this works, but
'substance' could be 'mica' (mica is a kind of substance) and 'mica' is present in the answer.
'location' could be 'col' (col is a kind of location) and 'col' is present in the leftover letters.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for comical that I've seen before include "Amusing or droll" , "Witty" , "Causing laughter" , "Rich" , "'Amusing, funny (7)'" .)