English tenor enthralled by sailor's instruments (5)
I believe the answer is:
oboes
'instruments' is the definition.
(oboe is a kind of instrument)
'english tenor enthralled by sailor's' is the wordplay.
'english tenor' becomes 'boe' (singer Alfie Boe. I am not sure about the 'english' bit.).
'enthralled by' is an insertion indicator ('enthral' can mean 'capture').
'sailor' becomes 'os' (ordinary seaman).
'boe' inserted into 'os' is 'OBOES'.
Can you help me to learn more?
(Other definitions for oboes that I've seen before include "Reed instruments" , "Wind instruments" , "Woodwind instruments" , "noted producers" , "They're instrumental" .)