A fellow that's poor can be passionate (6)
I believe the answer is:
aflame
'be passionate' is the definition.
(similar in meaning)
'a fellow that's poor' is the wordplay.
'fellow' becomes 'f' (abbreviation - of a society etc.).
'that's poor' becomes 'lame'.
'a'+'f'+'lame'='AFLAME'
'can' is the link.
(Other definitions for aflame that I've seen before include "Indicating excitement" , "Ma, flea could be burning" , "Ablaze" , "Ardent" , "On fire" .)