One heading to bed on board craft on delta (4)
I believe the answer is:
dart
'one heading to bed on board' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'craft on delta' is the wordplay.
'craft' becomes 'art' (both can mean cunning or trickery).
'on' is a charade indicator (letters next to each other).
'delta' becomes 'd' (phonetic alphabet: alpha, bravo, charlie etc.).
'art' after 'd' is 'DART'.
Can you help me to learn more?
(Other definitions for dart that I've seen before include "Move along rapidly and lightly" , "One fired" , "Move quickly and suddenly" , "Small arrow" , "Tuck; arrow" .)