Body of rook found in small wood (6)
I believe the answer is:
corpse
'body' is the definition.
(a corpse is a dead body)
'rook found in small wood' is the wordplay.
'rook' becomes 'r' (abbreviation in chess).
'found in' indicates putting letters inside.
'small wood' becomes 'copse' (small woodland area).
'r' inserted into 'copse' is 'CORPSE'.
'of' is the link.
(Other definitions for corpse that I've seen before include "Cadaver, dead person" , "Dead body" , "Roof beam" , "Dead bodies" .)