Put wood back? Relax after taking in warning (8)
I believe the answer is:
reforest
'put wood back?' is the definition.
(I've seen this before)
'relax after taking in warning' is the wordplay.
'relax' becomes 'rest' (to relax is to have a rest).
'after taking in' indicates putting letters inside.
'warning' becomes 'fore' (shouted in golf).
'rest' enclosing 'fore' is 'REFOREST'.
(Other definitions for reforest that I've seen before include "Plant again with trees" , "put wood back?" , "put new trees in!" .)