Thanks Jono, and apologies for the late response - I got distracted and have only just come back to the crossword.
17a - Well, I think the homophone is pretty poor! Though it would have worked better if the clue had read: 'Pilgrimage venue enticed', which would still have worked as a surface, I feel, and would have made a lot more sense.
12d - I would never have worked out that it was a hidden! Very clever.
11a - got it as soon as I read your hint - I'm really rubbish at spoonerisms!