Clue: Suspect guerrilla's left to become resistance fighter (9)
Answer: IRREGULAR
Explanation: Definition: resistance fighter
***(guerrila r)** [anag:*suspect*] which is guerilla with one of the Ls (for left) gone, however, I can't see anything telling us to remove the L? 
*Edit: Going back to the previous blog, I see that the solution is simply "fighter", with the "left to become resistance" part indicating that we need to replace an L with an R