Meet and speak about irrational fits (7)
I believe the answer is:
satisfy
'meet' is the definition.
(satisfying is a kind of meeting)
'speak about irrational fits' is the wordplay.
'speak' becomes 'say' (I've seen this in other clues).
'about' means one lot of letters goes inside another.
'irrational' indicates anagramming the letters.
'fits' is an anagram of 'tisf'.
'say' enclosing 'tisf' is 'SATISFY'.
'and' is the link.
(Other definitions for satisfy that I've seen before include "Please; comply with" , "Fulfil requirements" , "Meet, comply with" , "Meet the needs of (someone)" , "Quench, sate" .)