f = #2 + #^2 / #3 & @@ # & ;

f[ {a, b, c} ]

Out[]= b + a^2 / c

f = #2 + #^2 / #3 @@& ;

In[1]:= Needs["Notation`"]

In[2]:= Notation[x_ [Wolf] [DoubleLongLeftRightArrow] (x_ @@ # &)]

In[3]:=  f=#2+#^2/#3& [Wolf]
Out[3]= (#2+#1^2/#3&) [Wolf]

In[4]:= f[{a,b,c}]
Out[4]= b+a^2/c