String player united a couple of quintets to appear in catalogue (8)
I believe the answer is:
lutenist
'string player' is the definition.
(someone playing a lute)
'united a couple of quintets to appear in catalogue' is the wordplay.
'united' becomes 'U' (as in Man U, Manchester United).
'a couple of quintets' becomes 'ten' (I am not sure about this - if you are sure you should believe this answer much more).
'to appear in' indicates putting letters inside.
'catalogue' becomes 'list' (a catalogue is a list of items).
'u'+'ten'='uten'
'uten' going into 'list' is 'LUTENIST'.
Can you help me to learn more?
(Other definitions for lutenist that I've seen before include "Plucky player" , "Stringed instrument player" , "Stringed-instrument player" , "Instrumentalist" .)