In the garden, he adds a touch of imagination (5)
I believe the answer is:
gnome
This clue could be a double definition.
'in the garden he adds a' is the first definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'touch of imagination' is the second definition.
The definition and answer can be both related to communication as well as being singular nouns.
Perhaps you can see a link between them that I don't see?
Can you help me to learn more?
(Other definitions for gnome that I've seen before include "Dwarfish creature; garden ornament" , "Creature in garden (or Zurich?)" , "Little garden man?" , "Hobgoblin" , "Swiss financier" .)