The 24-year-old, who has played 10 tests for New Zealand since his debut against Wales in 2009, will leave at the end of the Super Rugby season with the Crusaders. He is contracted to the NZRU until the end of 2014 but has an out-clause with Hawkes Bay and has chosen to exercise that.
It's hard to argue with Guildford's move. He has had a troubled time over the past few years, with a number of alcohol-related incidents, and he might be looking for a fresh start as well as a chance to cash in at his stage in his professional career.
He is also behind a number of good, young wings on the New Zealand scene like Julian Savea, Ben Smith, Cory Jane and Frank Halai, and had long been linked with a move overseas.
"It's never OK to be losing talented rugby players but Zac has to do what is best for him," Hawkes Bay Rugby Union chief executive Mike Bishop said.
"He goes with our blessing. He's been a favourite son of ours for the past six or seven years. We would have loved to have seen him stay and play out the rest of his career with us but he's always welcome back here."
Guildford made his Hawkes Bay debut in 2007 as an 18-year-old and he was also a member of the gold medal-winning New Zealand sevens team at the 2010 Commonwealth Games.
Clermont will reportedly announce the move overnight (NZT) and it's expected he has been signed to replace former All Black wing Sitiveni Sivivatu, who is moving to Castres.
