A jazzy ensemble gathering ace ratings (4,6)
I believe the answer is:
able seamen
'ratings' is the definition.
(rating can mean a sailor)
'a jazzy ensemble gathering ace' is the wordplay.
I cannot really see how this works, but
'a' is within the answer.
'ace' could be 'a' (abbreviation) and 'a' is found in the answer.
an anagram of 'ensemble' is 'blesemen' which is within the remaining letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for able seamen that I've seen before include "sailors" , "ratings" .)