### Clue: Fish one decimated when penultimate is caught (5)
### Answer: TENCH 
 ### Explanation: Definition: Fish
 "tenth"(1 decimated;divided by 10) **with its last but one letter changed to**(when penultimate is) "c"(abbrev. for "caught" in cricket scores). Should there be an indicator for the replacement of the second "t" in "tenth"? Eg. "Fish ….. is caught instead", or some such.