Reportedly understand the Irish, say (3)
I believe the answer is:
sea
'irish say' is the definition.
(the Irish Sea is an example)
'reportedly understand' is the wordplay.
'reportedly' indicates a 'sounds like' (homophone) clue.
'understand' becomes 'see' (synonyms).
'see' is a homophone of 'SEA'.
'the' is the link.
(Other definitions for sea that I've seen before include "Cause of flooding" , "Large body of salt water" , "The Aegean, for example" , "The drink" , "Eg, Aral, Ross, Irish" .)