Better for rascal to wander (7)
I believe the answer is:
improve
'better' is the definition.
(I know that better can be written as improve)
'rascal to wander' is the wordplay.
'rascal' becomes 'imp' (synonyms).
'to wander' becomes 'rove' ('rove' can be a synonym of 'wander').
'imp'+'rove'='IMPROVE'
'for' is the link.
(Other definitions for improve that I've seen before include "Ameliorate" , "Make progress" , "Polish" , "Train" , "reform" .)