Be told to announce it's only a rumour (7)
I believe the answer is:
hearsay
'rumour' is the definition.
(synonyms)
'be told to announce' is the wordplay.
'be told' becomes 'hear' (I've seen this in another clue).
'to announce' becomes 'say' (I've seen this in another clue).
'hear'+'say'='HEARSAY'
'it's only a' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for hearsay that I've seen before include "rumoured" , "Kind of rumour, makes bad evidence" , "Rumour or gossip - inadmissible as evidence" , "Testimony not based on direct knowledge" , "Gossip or rumour - not allowed as evidence" .)