Andrew and I get on — it's a match! (8)
I believe the answer is:
marriage
'a match' is the definition.
(thesaurus)
'andrew and i get on' is the wordplay.
'andrew' becomes 'marr' (Andrew Marr).
'and' is a charade indicator (letters next to each other).
'get on' becomes 'age' ('age' can be a synonym of 'get on').
'marr'+'i'+'age'='MARRIAGE'
'it's' is the link.
(Other definitions for marriage that I've seen before include "'The - - of Figaro'" , "Church occasion" , "The nuptial ceremony" , ""Till death do us part" arrangement" , "Formal union" .)