On the road, Jack needs a raincoat (6)
I believe the answer is:
tarmac
'on the road' is the definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.
'jack needs a raincoat' is the wordplay.
'jack' becomes 'tar' (both are informal terms for sailor).
'needs' says to put letters next to each other.
'a raincoat' becomes 'mac' (macintosh is a type of raincoat).
'tar'+'mac'='TARMAC'
Can you help me to learn more?
(Other definitions for tarmac that I've seen before include "Road-surfacing material" , "Road-surfacing substance" , "Surfaced area as for planes to take off and land" , "black one" , "short runway, perhaps" .)