Drug old man worsening after tattoo (10)
I believe the answer is:
painkiller
'drug' is the definition.
(painkiller is a kind of drug)
'old man worsening after tattoo' is the wordplay.
'old man' becomes 'pa' (both can mean someone's father).
'worsening' becomes 'iller' (I can't explain this - if you can you should believe this answer much more).
'after' is a charade indicator (letters next to each other).
'tattoo' becomes 'ink' (ink can informally mean a tattoo).
'iller' put after 'ink' is 'inkiller'.
'pa'+'inkiller'='PAINKILLER'
Can you help me to learn more?
(Other definitions for painkiller that I've seen before include "Aspirin, for instance" , "Aspirin maybe" , "soothing drug" , "form of medicine" , "Analgesic drug" .)