For Friday's crucial ESB International clash, recent Connacht debutant Tiernan O'Halloran will make his first start of the campaign on the left wing.
There is also a new look to the front row as Jack O'Connell moves from tighthead to loosehead prop, with Stewart Maguire being promoted from the replacements for his first start, taking over from Bryan Cagney.
There are two new faces on the bench with Leinster's Risteard Byrne and Gareth Quinn McDonogh from Munster coming into the matchday 22 for the first time.Speaking of his selection and of the task at hand, Clarke said: "Whilst the decision to alternate the squad was given much consideration, the changes reflect the quality of the player group.
"Planning and preparation has gone well. There is an appetite within the squad to continually develop as individuals and as a team.
"The attention to detail and focus to improve reflect the respect we have for Wales and the squad ambition to build on our performances in the Championship."
Having beaten a highly-fancied England side 25-10 in Gloucester last time out, Ireland currently top the table on points difference, ahead of England and Wales on four points apiece.IRELAND UNDER-20 Team & Replacements (v Wales U-20, RBS U-20 6 Nations Championship, Dubarry Park, Friday, March 12, kick-off 7.35pm):
15 - Andrew Conway (Blackrock College/Leinster)
14 - Darren Hudson (St. Mary's College/Leinster)
13 - Brendan Macken (Blackrock/Leinster)
12 - Nevin Spence (Ballynahinch/Ulster)
11 - Tiernan O'Halloran (Galwegians/Connacht)
9 - John Cooney (UCD/Leinster)
1 - Jack O'Connell (Lansdowne/Leinster)
2 - Niall Annett (Belfast Harlequins/Ulster)
3 - Stewart Maguire (Old Belvedere/Leinster)
4 - David O'Callaghan (UCC/Munster)
5 - Ben Marshall (UCD/Leinster)
6 - Rhys Ruddock (UCD/Leinster) (capt)
7 - Dominic Ryan (Lansdowne/Leinster)
8 - Patrick Butler (Shannon/Munster)
16 - Risteard Byrne (UCD/Leinster)
17 - Bryan Cagney (UCC/Munster)
18 - Brian Hayes (Cork Constitution/Munster)
19 - Robin O'Sullivan (Bective Rangers/Leinster)
20 - Michael Heaney (Belfast Harlequins/Ulster)
21 - Gareth Quinn McDonogh (Shannon/Munster)
22 - Eoin Griffin (Corinthians/Connacht)