One possibly tending to be poor (8)
I believe the answer is:
indigent
'poor' is the definition.
(indigent means poor or needy)
'one possibly tending' is the wordplay.
'one' becomes 'i' (Roman numeral).
'possibly' indicates anagramming the letters.
'tending' with letters rearranged gives 'ndigent'.
'i'+'ndigent'='INDIGENT'
'to be' is the link.
(Other definitions for indigent that I've seen before include "Badly off" , "Poor enough to need help from others" , "Impoverished, destitute" , "Impoverished -- ending it (anag)" , "Poor and needy" .)