Hardly the type to make a good lookout (9)
I believe the answer is:
introvert
'lookout' is the definition.
The definition and answer can be both people as well as being singular nouns.
Maybe they are linked in a way I don't understand?
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for introvert that I've seen before include "quiet" , "Self-absorbed person" , "Rover tint (anag.)" , "one's reserved" , "Turn inwards" .)