Nasty type of slow approach (5)
I believe the answer is:
creep
This might be a double definition.
'nasty type' is the first 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?
'slow approach' is the second definition.
The answer and definition can be both to do with motion as well as being verbs in their base form.
Perhaps there's a link between them I don't understand?
'of' acts as a link.
Can you help me to learn more?
(Other definitions for creep that I've seen before include "narrow passage" , "Walk slowly, silently" , "Inch" , "Slink" , "Move silently and secretly" .)