Step 1: Set up alphabet positions.
Assign each letter its number, $A=1$ up to $Z=26$, so we can measure shifts.
Step 2: Read shifts from UP to WS (the shorter clue).
$U(21)\to W(23)$ is $+2$ and $P(16)\to S(19)$ is $+3$. The shift grows by one each step.
Step 3: Confirm with OVER to QYIW.
$O\to Q\,(+2)$, $V\to Y\,(+3)$, $E\to I\,(+4)$, $R\to W\,(+5)$. The pattern $+2,+3,+4,+5$ holds.
Step 4: Apply to S and T of STAR.
$S(19)+2=U(21)$ and $T(20)+3=W(23)$.
Step 5: Apply to A and R of STAR.
$A(1)+4=E(5)$ and $R(18)+5=W(23)$.
Step 6: Join the coded letters.
Reading them in order gives U, W, E, W.
\[ \boxed{\text{UWEW}} \]