One gets £50 for being sick (3)
I believe the answer is:
ill
'sick' is the definition.
(I know that sick can be written as ill)
'one gets ps50' is the wordplay.
'one' becomes 'i' (Roman numeral).
'gets' means one lot of letters go next to another.
'ps50' becomes 'll' (I can't justify this - if you can you should give a lot more credence to this answer).
'i'+'ll'='ILL'
'for being' is the link.
Can you help me to learn more?
(Other definitions for ill that I've seen before include "Misfortune" , "Badly diminished" , "Seasick" , "Valetudinarian" , "Under the weather" .)