s_pugh it is a very straightforward grid fill. The points in the preamble that are noteworthy include: each cell is a number less than 52, parts of clues need to be squared and added to together to form the entry, letters in clues are primes 51 it is too large)
therefore the entry is
A^2 + (A*A)^2 + (A*A*A)^2 + (A*A*A*A)^2 = 340
which is entered with 3 in the first cell and 40 in the second
[please take note crosswordsolver.org: these are the types of hints that are helpful to solvers, not stating A = 2 and the answer is to 1d is 340, as that does not help solvers improve with these advanced thematic crosswords/crossnumbers (if there is such a thing as the latter). When I came to this site a long time ago we decided almost intuitively as a group to help nurture rather than give answers away. The former has been lost over the years and I think should be encouraged, but at least we have kept away from the latter (each to their own I suppose)]