It's good to give fish to the sick (6)
I believe the answer is:
ailing
'the sick' is the definition.
(I've seen this before)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for ailing that I've seen before include "Infertile" , "Ill" , "Sickly, poorly" , "not doing very well" , "Troubled in mind or body" .)