For those who want to retire but can't? As for the rest, some will be put out by this!
I believe the answer is:
sleeping pill
'for those who want to retire but can't? as for the' is the definition.
The definition suggests a singular noun which matches the answer.
'rest some will be put out by this' is the wordplay.
I cannot really understand how this works, but
'rest' could be 'sleeping' (sleeping is a kind of rest) and 'sleeping' is present in the answer.
'will' could be 'll' and 'll' is located in the answer.
The remaining letters 'pi' is a valid word which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for sleeping pill that I've seen before include "Strong tranquilliser" , "Medication for dropping off" , "Insomnia cure" , "Sleeplessness cure" , "Night-time tablet" .)