It's hard to be penniless (5)
I believe the answer is:
stony
I believe this clue is a double definition.
'it's hard' is the first definition.
('stony' can be similar in meaning to 'hard')
'penniless' is the second definition.
(I've seen this before)
'to be' acts as a link.
(Other definitions for stony that I've seen before include "Rocky" , "Heartless" , "made of marble?" , "penniless" , "Cold, unfeeling" .)