Circus performers with fleece in a musical (8)
I believe the answer is:
acrobats
'circus performers' is the definition.
(I've seen this before)
'fleece in a musical' is the wordplay.
'fleece' becomes 'rob' (synonyms).
'in' is an insertion indicator.
'musical' becomes 'Cats' (Andrew Lloyd Webber musical).
'a'+'cats'='acats'
'rob' going inside 'acats' is 'ACROBATS'.
'with' is the link.
(Other definitions for acrobats that I've seen before include "Circus athletes or gymnasts" , "Gymnastic performers" , "versatile performers" , "Gymnasts; tumblers" , "Boast car (anag.)" .)