Series about one retro English band (6,4)
I believe the answer is:
signet ring
'band' is the definition.
(signet ring is a kind of band)
'series about one retro english' is the wordplay.
'series' becomes 'string' (sequence of similar items or events).
'about' means one lot of letters goes inside another.
'one' becomes 'i' (Roman numeral).
'retro' shows that the letters should be reversed in order (retro is Latin for 'backwards').
'english' becomes 'eng'.
'eng' backwards is 'gne'.
'i'+'gne'='igne'
'string' placed around 'igne' is 'SIGNET-RING'.
(Other definitions for signet ring that I've seen before include "band used to make impression" , "Item of jewellery, often engraved with an initial" , "it makes an impression" , "that 9,16 [QUEENS MARKER] reportedly uses" , "Personal seal" .)