Bit of greenery, perhaps, giving extra heart to another colour (4)
I believe the answer is:
reed
'bit of greenery perhaps' is the definition.
I can't tell whether this defines the answer.
'extra heart to another colour' is the wordplay.
'extra' becomes 'added' (something added is extra).
'heart' indicates the central letters.
'to' means one lot of letters go next to another (I've seen this in other clues).
'another colour' becomes 'ree' (I can't justify this - if you can you should believe this answer much more).
The middle of 'added' is 'd'.
'd' after 'ree' is 'REED'.
'giving' acts as a link.
Can you help me to learn more?
(Other definitions for reed that I've seen before include "Grass of marshes" , "Grassy plant of wet areas" , "Vibrator in the mouthpiece of a wind instrument" , "Tall stiff marsh or water grass" , "Slender grass of wet areas" .)