Uncertainties (6)
'uncertainties' is the definition.
(an if is an uncertainty or something in doubt)
This is the entire clue.
(Other definitions for ifs that I've seen before include "Suppositions, may be accompanied by buts" , "Conditional conjunctions" , "Conditions or suppositions, may join with buts" , "No ...,ands or buts, no argument allowed" , "If . . . and ands were pots and pans" .)
'uncertainties' is the definition.
(doubt is a kind of uncertainty)
This is the entire clue.
(Other definitions for doubts that I've seen before include "Thinks something unlikely" , "Isn't certain about, has reservations" , "Misgivings" , "Has reservations, is uncertain" , "Uncertainties" .)