Help about five to be greedy (4)
I believe the answer is:
avid
'greedy' is the definition.
(synonyms)
'help about five' is the wordplay.
'help' becomes 'aid' (synonyms).
'about' means one lot of letters goes inside another.
'five' becomes 'V' (Roman numeral).
'aid' placed around 'v' is 'AVID'.
'to be' acts as a link.
(Other definitions for avid that I've seen before include "Impassioned about diva" , "Showing a very keen interest in something" , "In operation" , "Ardent about diva" , "'Eager, enthusiastic (4)'" .)