The 20-year-old received the call yesterday
from US head coach Jurgen Klinsmann, ahead of their friendly fixture against Ukraine next week.
Packwood's selection comes just over a year since he suffered a career-threatening double leg-break
whilst playing for Blues against Leeds United.
"Everyone at the club is so happy for Will," said Clark.
"This time last year it was looking like a tough call for him in terms of his footballing future. We were all distraught because of the injury.
"For him to come back from an injury like he has hasn’t surprised me because when you have his desire, application and professionalism you’ve got a chance.
"Since he’s been back in the team in his real position he’s been outstanding since and this call-up is fully deserved. If he continues with the form that he’s shown and if Jurgen was to call me I’d say 'take him to the World Cup with America."