Timber a chap put in a car (5)
I believe the answer is:
cedar
'timber' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'a chap put in a car' is the wordplay.
'a chap' becomes 'Ed' (short for Edward).
'put in' is an insertion indicator (back).
'ed' put inside 'car' is 'CEDAR'.
Can you help me to learn more?
(Other definitions for cedar that I've seen before include "Cypress-like tree" , "Raced around a great hardwood tree" , "Tree giving fragrant wood" , "Tall coniferous tree" , "Evergreen tree" .)