He finds nuclear explosion like famous labours (9)
I believe the answer is:
herculean
'famous labours' is the definition.
The definition and answer are not the same part of speech.
'he finds nuclear explosion' is the wordplay.
'finds' means one lot of letters go next to another.
'explosion' indicates an anagram.
'nuclear' with letters rearranged gives 'rculean'.
'he'+'rculean'='HERCULEAN'
'like' is the link.
Can you help me to learn more?
(Other definitions for herculean that I've seen before include "So enormous a task" , "Showing great strength" , "Requiring very great effort" , "for Poirot?" , "Monumental (task)" .)