### Clue: Unseaworthy vessel's infection concealed presence of uranium (3)
### Answer: TUB 
 ### Explanation: Definition: Unseaworthy vessel
  TB(abbrev. for $$t$$u$$b$$ercolosis, an infectious disease caused by Mycobacterium tuberculosis, largely thought to be eradicated by mass vaccination, and antibiotics, but with some evidence of new strains resistant to those antibiotics) ***containing***(concealed presence of) U(in chemistry, symbol for $$u$$ranium)