To wander in small wood not good (4)
I believe the answer is:
rove
'to wander' is the definition.
('rove' can be a synonym of 'wander')
'small wood not good' is the wordplay.
'small wood' becomes 'grove' (I've seen this before).
'not' suggests deleting specific letters.
'good' becomes 'g' (abbreviation).
'grove' with 'g' taken away is 'ROVE'.
'in' acts as a link.
(Other definitions for rove that I've seen before include "Roam about aimlessly" , "Knock about" , "Range" , "Don't stay in one place" , "Wander or walk about" .)