English lad comes across knight in the wood (5)
I believe the answer is:
ebony
'wood' is the definition.
(ebony is a kind of wood)
'english lad comes across knight' is the wordplay.
'english' becomes 'e' (abbreviation).
'lad' becomes 'boy' (I've seen this before).
'comes across' is an insertion indicator.
'knight' becomes 'n' (chess).
'boy' placed around 'n' is 'bony'.
'e'+'bony'='EBONY'
'in the' acts as a link.
(Other definitions for ebony that I've seen before include "Hard block tropical wood" , "Black hardwood" , "'Hard, dark wood (5)'" , "Tree having black wood" , "Hard dark-coloured wood" .)