Clear hole-like shape alongside green (5)
I believe the answer is:
overt
'clear hole' is the definition.
'overt' can be an answer for 'clear' (both can mean apparent or obvious). I am not sure about the 'hole' bit.
'shape alongside green' is the wordplay.
'shape alongside' becomes 'o' (I can't justify this - if you can you should give a lot more credence to this answer).
'green' becomes 'vert' (heraldic term for green).
'o'+'vert'='OVERT'
'like' acts as a link.
Can you help me to learn more?
(Other definitions for overt that I've seen before include "Obvious, patent" , "Done or shown openly" , "Patent, evident" , "Open, not 1 across" , "Not locked away" .)