Worried voices about the heart of Manchester United (8)
I believe the answer is:
cohesive
'united' is the definition.
(similar in meaning)
'worried voices about the heart of manchester' is the wordplay.
'worried' indicates an anagram (worry can mean to interfere with or disturb).
'about' means one lot of letters goes inside another.
'the heart of' indicates the central letters.
The middle of 'manchester' is 'he'.
'voices' with letters rearranged gives 'cosive'.
'cosive' enclosing 'he' is 'COHESIVE'.
(Other definitions for cohesive that I've seen before include "All together, holding" , "Tending to stick together" , "Sticking together" , "United" .)