Help half of a group of characters (4)
I believe the answer is:
abet
'help' is the definition.
(thesaurus)
'half of a group of characters' is the wordplay.
'half of' suggests halving the letters.
'a group of characters' becomes 'alphabet' (I've seen this before).
'alphabet' with half the letters taken is 'ABET'.
(Other definitions for abet that I've seen before include "Assist (a criminal)" , "Assist (in wrongdoing)" , "helpful" , "Aid - connive with" , "Aid and assist" .)