In the description of Leadership special ability, it is mentioned that there must be a clear line of fire between the figure which resolve the action and the figure with the Leadership special ability. Is "clear line of fire" considered to be only clear terrain, or is it concealing and hindering too? So is Leadership only blocked from blocking terrain and other figures, or not?

CLEAR means clear. Figures and terrain,etc. would be blocking, so not clear.

I'm not 100% sure, but I think "clear line of fire" means not blocked by another figure's dial or blocking terrain. Just like how hindering terrain doesn't block LOS just gives a modifier for shooting through it, I don't think it will affect Leadership.

What would happen if the miniature has bound, and at the begining of the movement is within the range and front arc and clear line of fire of the one that posses leadership, but at the end of the movement is ends outside the range, front arc or with out clear line of fire? Does lidership only aplly for the beginig of the action? or for the entire action?

The figure which is given the action must be within 10 inches from the one with leadership. When you have given the action, it doesn't matter if it moves further, because the ability has already applied. About the "clear line of fire", I want to agree with Norim2, but I am not really sure about it. It is logical that as long as you can see a figure for other purposes, for example healing, when occupying hindering or concealing terrain, you can also use leadership for it. But the designer might have thought that the ability is too powerful, and so tried to limit it that way. I want more opinions about it. Any thoughts are wellcome.

A clear line of fire is a line of fire that is not blocked.

The term isn't outright defined, but in the Titan rules, there are certain figures with minimum and maximum range values that can make "indirect" attacks, and it says they can make a "ranged combat action targeting a single opposing warrior without needing a clear line of fire to the target." In this context it is obvious it's referring to a non-blocked line of fire, as they wouldn't need to do an indirect attack if they were just shooting through hindering/concealing terrain (the penalty they get from indirect fire is noticeably more with indirect fire).

A question in the FAQ about Arc Lightning also uses this definition of "clear line of fire" (ie, unblocked).

Thanks Sigma, I think you gave the answer to my question.