Poor average (4)
I believe the answer is:
mean
I believe this is a double definition.
'poor' is the first definition.
(similar in meaning)
'average' is the second definition.
(type of average)
(Other definitions for mean that I've seen before include "Unkind; average" , "Signify; stingy" , "Spiteful -- excellent (slang)" , "spell" , "Stingy in average way" .)