Being infirm, succumb about the end of the year (5)
I believe the answer is:
frail
'being infirm' is the definition.
(similar in meaning)
'succumb about the end of the year' is the wordplay.
'succumb' becomes 'fail' (I can't justify this - if you can you should give a lot more credence to this answer).
'about' means one lot of letters goes inside another.
'the end of' suggests the final letters.
The final letter of 'year' is 'r'.
'fail' going around 'r' is 'FRAIL'.
Can you help me to learn more?
(Other definitions for frail that I've seen before include "Feeble - basket" , "Weak, feeble" , "Physically feeble" , "hobbling around?" , "American woman" .)