9a Syrian garments showing down! (4)
ABA _
(not in my dictionary!)
20d He utters gibberish, rough speech including indistinct words mum missed (7)
B _ R _ LER
I presume this is burbler (he utters gibberish) and I can see burr (rough speech) but Ble ?
28a In the ground, what’ll catch e.g. moles, thrashing no longer (8)
_ TRA _ (H)I _
(I am not 100% sure of the H)
26 Feature of Cape gooseberry? Cook before middle of lunch (5) _ _ ORN
I think this is "thorn" but can't parse. Thor = cook. why ?
27d 27 Southern poet and dramatist in artful style (5) _ _ YLY
(There is a note, "two proper names may be unfamiliar to some". I think this is one of them!)