In favor of (3)
I think it could be either:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">in favor of</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for pro that I've seen before include "Top player" , "Competent person" , "Expert (abbr)" , "Athelete who plays for pay" , "Preposition meaning for, in favour of" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">in favor of</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for for that I've seen before include "On the side of" , "and 16 and 20: Notwithstanding" , "In favour of; since" , "Favouring" , "On behalf of" .)