He painted truck green with greyish coat (3,4)
I believe the answer is:
van gogh
'he painted' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'truck green with greyish coat' is the wordplay.
'truck' becomes 'van' (van is a kind of truck).
'green with' becomes 'go' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'coat' suggests removing the centre (only the letters which coat the word are used).
'greyish' with its middle removed is 'gh'.
'van'+'go'+'gh'='VAN GOGH'
Can you help me to learn more?
(Other definitions for van gogh that I've seen before include "Painter of Irises and The Potato Eaters" , "Vincent ... ...., Dutch painter who cut off his ear" , "picture maker" , "Dutch post-impressionist painter" , "Dutch painter, d. 1890" .)