Ian McKinley, who kicked four penalties against Wales, will lead the team in the injury-enforced absence of regular captain Peter O'Mahony.
David Kearney moves to full-back in place of Ian Madigan with Ronan O'Mahony coming into the side on the right wing.
Up front Joe Moran starts in the second row alongside Mark Flanagan, while the back row sees David O'Callaghan and Dominic Ryan come in for the injured Brian O'Hara and O'Mahony.
Speaking ahead of the 7th-8th place play-off, head coach Clarke said: "We'll prepare as best we can for an important game on Sunday, we've got seventh place to fight for now.
"Against Wales we didn't get to the level, in terms of our game, that we aspired to and the level that we showed against New Zealand.
"However, we've got to regroup. That is what sport's about - it's about recovering physically and mentally so that these players, who had a really good season, finish it on a high."
IRELAND UNDER-20 TEAM & REPLACEMENTS (v Samoa, IRB TOSHIBA Junior World Championship, Sunday, June 21, Level 5 Stadium, Fukuoka, kick-off 12pm local time/4am Irish time):
15 - David Kearney (Lansdowne/Leinster)
14 - Ronan O'Mahony (Garryowen/Munster)
13 - Danny Barnes (UCC/Munster)
12 - Eamonn Sheridan (Lansdowne/Leinster)
11 - Michael Keating (Clontarf/Leinster)
10 - Ian McKinley (UCD/Leinster) (capt)
9 - Matthew Healy (Lansdowne/Leinster)
1 - Jack McGrath (St.Mary's College/Leinster)
3 - Adam Macklin (Belfast Harlequins/Ulster)
4 - Joe Moran (Galwegians/Connacht)
5 - Mark Flanagan (UCD/Leinster)
6 - David O'Callaghan (UCC/Munster)
7 - Dominic Ryan (Lansdowne/Leinster)
8 - Rhys Ruddock (Millfield School/Exiles)
16 - David McGregor (Ballynahinch/Ulster)
17 - Paddy McAllister (Ballynahinch/Ulster)
18 - Jack O'Connell (Lansdowne/Leinster)
19 - Brian Hayes (CBC/Munster)
20 - Conor Murray (Garryowen/Munster)
21 - Ian Madigan (Blackrock College/Leinster)
22 - Shane Gahan (Lansdowne/Leinster)