Seen in Scottish mountain, a runner? (4)
I believe the answer is:
bean
'runner?' is the definition.
The definition and answer can be both plants as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'seen in scottish mountain a' is the wordplay.
'seen in' indicates putting letters inside.
'scottish mountain' becomes 'ben' (Scottish term for a peak, eg Ben Nevis).
'ben' enclosing 'a' is 'BEAN'.
Can you help me to learn more?
(Other definitions for bean that I've seen before include "Fava, kidney or mung, say" , "Haricot, for example" , "Kidney-shaped seed as for coffee" , "Haricot seed" , "Vegetable; coffee seed" .)