A cat, I see, is like a bomb! (6)
I believe the answer is:
atomic
'bomb' is the definition.
(thesaurus)
'a cat i see' is the wordplay.
'cat' becomes 'tom' (a tom is a male cat).
'see' becomes 'C' (the word for the letter, according to Chambers).
'a'+'tom'+'i'+'c'='ATOMIC'
'is like a' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for atomic that I've seen before include "Based on nuclear energy" , "Like some clocks" , "Extremely small-scale" , "of bombs" , "Relating to tiny particles" .)