3d Jack's jack in laureate's verse (3. 5) ??A ?E?E? Why would it be SEA LEVEL?
28a Reliable restorer of old manuscripts (9) ??L?O?A?E SELLOTAPE?
23a Italian artist designed and built his own gallery (6) ???S?I
10a Fleece keeper gets set back by Irish poet (5) A?T??
I found this quite a lot harder than usual. Thanks.
For 3d, John (Jack?) Masefield's 'Sea Fever' looks promising but I can't see the connection to the second 'jack'. Neither can I see why SANDS for 1a and SELLOTAPE for 28a. I've already voiced my concerns about SAGA (19a) elsewhere. I'm obviously struggling with what, to others, are obvious answers.
Belated thanks to all and answer to slaney: the 'S' comes from SATAN Continue to play with a name for Bronte. Only thing I could think of, but a bit thin even for TLS.