Elastic gets old for uniform, a worry for security guard? (7)
I believe the answer is:
robbery
'guard?' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Perhaps there's an association between them I don't understand?
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for robbery that I've seen before include "Theft maybe with violence" , "Theft crime" , "Theft, stealing" , "Theft of property" , "Criminal action" .)