Wait on, needing time to finish (4)
I believe the answer is:
tend
'wait on' is the definition.
(thesaurus)
'time to finish' is the wordplay.
'time' becomes 't'.
'to finish' becomes 'end' ('end' can be a synonym of 'finish'**).
't'+'end'='TEND'
'needing' is the link.
(Other definitions for tend that I've seen before include "Incline - mind" , "Be predisposed or inclined" , "Minister" , "Incline; cultivate" , "Look after (a patient)" .)